Living to 100 years old seems completely miraculous on its own, so you'll be totally stunned when you meet this inspiring woman named Lil Hansen, who just turned 105 and is teaching 70- and 80-year-olds yoga!  Lil flows effortlessly from Warrior 1 to Triangle and says, "I don't feel old," adding, "I don't think about it.  I just keep going."  Bless her sweet little heart.  We should all be so lucky to have her exceptional health, strength, flexibility, independence, and positive energy at that age!

When it comes to high-intensity interval training (HIIT), the pros definitely outweigh the cons.  While it may feel unpleasant to push your body to go faster and harder for that short time period, the rewards are worth it:  HIIT helps you blast more belly fat, save time, and burn way more calories than a lower-intensity workout alone.  A new study published in the American College of Sports Medicine's Health and Fitness Journal found that a few minutes of training at almost your max can accomplish all of this in way less time than a traditional workout.  How much less?  Try just seven minutes total.  The ACSM's interval workout consists of 12 exercises, which should be done at an intensity of 8 on a scale of 10;  each exercise lasts 30 seconds, with a 10-second rest in between.  Repeat the circuit if you'd like a longer workout.  Keeping the intensity up — and the rest periods short — is key, so click through to learn the moves and then get going!  You'll need a mat and a chair or bench.

1. Jumping Jacks

Warm up your body with a vigorous stint of jumping jacks.  Do these for a total of 30 seconds.

2. Wall Sit

• Stand with your back against a wall, placing your feet about two feet out in front of you.  Feet should be hip-distance apart.
• Bending your knees, slide your back down the wall until your knees are at 90-degree angles.  Your knee joints should be over your ankle joints, so you may need to inch your feet further from the wall to create proper alignment.  Don't let your knees fall in on the midline of your body, or sway outwards.
• Hold for 30 seconds.

3. Push-Up

• Start in a plank position, with palms spread out evenly and your shoulders over your wrists and legs out behind you.  Pull your belly button in and keep your back straight.
• As you lower and exhale, bend your elbows outward to the sides.  Hold at the bottom before you raise back up.
• Do as many reps as possible in 30 seconds.

4. Crunches

• Sit on your mat and bend your knees, planting your feet on the floor.  Put your palms behind your ears.
• As you exhale, pull your abs in and lift your upper body.  Inhale as you lower back down.
• Keep your chin down to keep your neck from straining, and make sure your ribs are aligned with your hips.
• Do as many reps as you can in 30 seconds.

5. Chair Step-Ups

• Find a step, a bench, or a sturdy chair that when you place your foot squarely on it your knee is at a 90-degree angle or larger.
• Step up 20 times leading with the right foot, then the left, bringing both feet completely onto the bench.  To return to the starting position, lead with the right foot to step down to the floor, then the left, until ending with both feet on the ground.  Switch legs and start stepping with the left foot for 20 steps.
• To make this move more challenging, start by stepping onto the bench with your right foot, bring your left foot up and tap the bench with your left toes, then lower your left foot down to tap the floor (as shown).  This is one rep.  Your right foot never moves as you bend and straighten your right knee.This works best on a step or bench, something lower than a chair.
• Repeat either move for a total of 30 seconds.

6. Squat

• Stand with your head facing forward and your chest held up and out.
• Place your feet shoulder-width apart or slightly wider.  Extend your hands straight out in front of you to help keep your balance.  Sit back and down like you're sitting into an imaginary chair.  Make sure your head stays facing forward, not down (focus on something in front of you to help) and that your upper body faces forward as well, bent slightly forward.  Rather than allowing your back to round, let your lower back arch slightly as you descend.
• Lower down so your thighs are as parallel to the floor as possible, keeping your knees over your ankles.  Press your weight back into your heels.
• Keep your body tight, and push through your heels to bring yourself back to the starting position.

7. Triceps Dips

• Position your hands shoulder width apart on a secured bench or stable chair.
• Move your bum in front of the bench with your legs bent and feet placed about hip width apart on the floor.
• Straighten out your arms and keep a little bend in your elbows in order to always keep tension on your triceps and off your elbow joints.
• Now slowly bend at your elbows and lower your upper body down towards the floor until your arms are at about a 90-degree angle.  Be sure to keep your back close to the bench.
• Once you reach the bottom of the movement, slowly press off with your hands, and push yourself straight back up to the starting position.
• Repeat as many times as you can for 30 seconds.

8. Plank

• Lie face down on the floor or face your mat on your knees.  Place your palms so that your shoulders are aligned with your wrists close to your head.
• Push off the floor, raising up off your knees onto your toes and spreading your fingers and pressing down with your palms.  You can also try resting on your forearms as shown.
• Contract your abdominals and pull your belly button in to keep yourself up and prevent your booty from sticking up.
• Keep your back flat and hold for 30 seconds.

9. High Knees/Running in Place

Time for more cardio.  March (also called high knees) or run in place for 30 seconds.

10. Lunge

• Keep your upper body straight, with your shoulders back and relaxed and chin up (pick a point to stare at in front of you so you don't keep looking down).  Always engage your core.
• Step forward with one leg, lowering your hips until both knees are bent at about a 90-degree angle.  Make sure your front knee is directly above your ankle, not pushed out too far, and make sure your other knee doesn't touch the floor.  Keep the weight in your heels as you push back up to the starting position.
• Repeat for a total of 30 seconds.

11. Push-Up Rotation

• Start in a plank position, with palms spread out evenly and your shoulders over your wrists and legs out behind you.  Pull your belly button in and keep your back straight.
• As you lower and exhale, bend your elbows outward to the sides.  Hold at the bottom for one breath.
• Raise back up to top push-up position.  As you reach the top, keep moving in a fluid motion to side plank position:  release your left arm and raise it to the ceiling, keeping your body in a long diagonal line.  Hold for one breath, then move back into push-up position.
• Repeat as many as you can, alternating which arm you are raising, for 30 seconds.

12. Side Plank

• Begin in a plank position (the top of a push-up) and roll over to your left side and plant your left heel down so you are balancing on the outside edge of your left foot.  Stack your right foot on top of your left.  If this is too hard, bend your left knee and place your left foot flat on the ground in front of your right leg for support.
• Keep your right arm on your side as shown or reach it straight up toward the ceiling to lift your waist even more.
• Press your left fingertips into the floor to take pressure out of your wrist.
• Hold for 30 seconds.

There's something so pure and wholesome about doing yoga in the nude, and these professional black and white photos capture the striking beauty and energy brilliantly.  We promise, these are totally #SFW.

Ten moves.  10 reps each.  Sounds simple enough, but man, your arms will be toast after completing 100 reps without a rest.  Modify this workout to fit your ability level by using two- to 4.5 kilo dumbbells.  Use the same size dumbbell for all 10 exercises (I used 3 kilo ones), or switch between lighter and heavier weights depending on the move.  If this is still too hard, do five reps for each move instead of 10.

Donkey Kicks

• From a standing position, bend at the hips and place your palms flat on the floor in a short Down Dog position.  Make sure your fingers are spread wide and you're pressing firmly into the fingertips.  Gaze at a spot on the floor slightly in front of you.
• Gently rock your weight forward as you push off the balls of the feet, trying to get space between your feet and the floor.  Take small hops at first to get comfortable with having all your bodyweight in your hands.
• Take bigger hops as you're ready.  Think about getting the hips over the shoulders, and, if possible, bring the soles of the feet to clap together.  Use the core to slowly and softly lower the feet back to the floor.
• Take 10 hops.

Upright Row

• Stand with your feet hip-distance apart, and place a dumbbell in each hand.  Your closed palms should be facing your body.  The shoulders should be over your pelvis, with knees slightly bent.
• Keeping the dumbbells close to your body, raise them to your shoulders, bending your elbows out to the sides.
• Slowly lower them to the starting position.  This counts as one rep.
• Perform 10 reps.

Overhead Triceps Extensions

• Stand with your feet hip-distance apart.
• Hold one dumbbell (go for your heavier weight) with both hands, bending the elbows behind your head.
• Straighten your arms to lift the dumbbell into the air, then slowly bend the arms to lower.  This counts as one rep.
• Complete 10 reps.

Wide Bicep Curl

• Stand with your feet slightly wider than hips-width-distance apart.
• Holding a dumbbell in each hand, hold the arms out wide with a slight bend in the elbows, palms facing up.
• Bend at the elbows, pulling the weights toward your ears.
• Extend the arms out wide again to complete one rep.
• Do 10 reps.

Overhead Shoulder Press

• Hold a dumbbell in each hand just above the shoulders, palms facing in.
• Straighten the arms above you.
• Bend the elbows coming back to the starting position to complete one rep.
• Do 10 reps total.

Bent-Over Reverse Fly

• Holding a dumbbell in each hand, stand with the knees slightly bent.  Keeping your back flat, bend forward at the hip joint.
• Exhale and lift both arms to the side, maintaining a slight bend in the elbows and squeezing your shoulder blades together.  Then, with control, lower the dumbbells back toward the ground.  This completes one rep.
• Perform 10 reps.

Triceps Kickback

• Holding a dumbbell in each hand, hinge forward from your hips, bending the knees slightly.  Bend your elbows behind you.
• Straighten your arms behind you with your palms facing in.  Your arms should be parallel to the floor.  Squeeze your triceps, and then return to the starting position.
• This counts as one rep.
• Complete 10 reps.

Bicep Curl

• Start by holding a dumbbell in each hand at the sides of the body.
• Keeping your elbows close to your side, slowly raise the dumbbells to the chest.
• Moving with control, lower back to the starting position.
• This counts as one rep.
• Complete 10 reps.

Single-Leg Scarecrow

• Stand on your left leg, and lift your right knee up until it is level with your hip.  Holding a dumbbell in each hand, raise your arms out to the side until your upper arms are parallel to the ground.  Bend your elbows to 90 degrees.
• Maintaining a strong sense of balance, rotate your upper arms forward to bring your fists to the floor, then rotate the upper arm backward to bring the fists up.  Do not lower or raise your upper arms;  keep them parallel to the floor.  This completes one rep.
• Do five reps, then switch legs by lifting the left leg up, and stand on the right foot for another five reps to complete the set.

Lying Chest Fly

This move looks relaxing, but it'll give your chest a little lift.

• Lie on your back with your hips and knees both at 90-degree angles.  Using your low abs, press your lower back into the mat.  Raise your arms toward the ceiling, palms facing each other, keeping the elbow joint slightly bent.
• Keeping your torso stable, open your arms out to the sides until your elbows are about two inches from the floor.
• Raise your arms back to the ceiling, bringing the weights together over your chest.  This counts as one rep.
• Perform 10 reps.

Don't think you have time to work out?  Think again.  These tips from top trainers will help you rethink all those excuses and start seeing results.  At least one of these tips will resonate with you, so keep it in mind the next time you're feeling overwhelmed and ready to skip your workout.

1. Schedule something almost every day:  You know you're not going to see results if you don't put in the time, so be realistic about what it's going to take.  The Biggest Loser:  Australia trainer Michelle Bridges recommends scheduling out a one-hour workout, six days a week.  It may seem like you don't have time for this, but putting these workouts on your calendar and aiming to hit the goal every week means you'll work out more than if you aimed for just two or three workouts a week — even if you have to skip.  "I guarantee that someone who has the habit of training six days a week, even if they miss a couple, is going to be more consistent than someone who only trains three days a week," Michelle says.
    
2. Stop with the excuses:  You say you don't have time to work out?  You may be making an excuse that has no leg to stand on, says celebrity trainer Gunnar Peterson, who's trained everyone from Sofia Vergara to Jennifer Lopez.  "Five minutes for a warmup, 30 minutes for a workout, and five minutes for a stretch and a cooldown.  By the end, that's 40 minutes," Gunnar says.  "You really don't have 40 minutes?  The President is far busier than you, Kim Kardashian is far busier than you, and she can make time.  It's about prioritising."
    
3. Every bit counts:  You may not have time to fit in a workout every day, but you do have time to walk, says celebrity trainer Harley Pasternak.  Invest in a simple pedometer — you don't even have to spend hundreds on an activity tracker;  a basic $25 pedometer (or a free app on your phone) can track your steps just as well.  Aim for 10,000 steps a day, and you'll start seeing a difference even if you have to skip a workout or two.
    
4. Aim high:  Just because you're busy doesn't mean you can't vocalise your goal of running a marathon or losing 15 kilos.  "It's good to set realistic goals, but sometimes you have to set unrealistic goals," says celebrity trainer Kacy Duke.  "Set goals that really feel like you're keeping it interesting and you're really pushing yourself at the same time."
    
5. Vary your intensity:  Get a better workout in the same amount of time as a regular workout by just varying your intensity.  "You're supposed to vary levels of exertion in order to optimally burn fat," says Joey Gonzalez, chief operating officer of celeb favourite Barry's Bootcamp.  "These kinds of things all date back to the caveman days when that's how you'd hunt ... That's how the human body responds."
    
6. Go with weights:  Want to see results fast?  Time to hit the weight room.  Miss America 2013's trainer, Tia Falcone, believes this is the fastest way to your slimmest self.  "All women need to gain as much muscle as humanly possible;  that's what's going to make you smaller, and it raises your base metabolism permanently," she says.
    
7. Above all, keep it manageable:  We love this tip from celebrity Pilates trainer Kit Rich, who's shared her own struggles with fluctuating weight and body issues:  aim for three miles of running, hiking, or walking, or 30 minutes of any kind of workout, every day.  "I really do believe wholeheartedly that the middle road is the way to go," she says.  "Anything extreme is not long-lasting."