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20s
"Hips and thighs start to change," Anderson says; shape them with:

SECOND-POSITION PLIÉS
Stand with feet just wider than shoulders, toes facing out, hands on hips. Squat to knee level, then straighten; do 80 to 100 reps.

BUTT PULSE
Holding the back of a chair for balance, extend one leg straight behind you. Point your toe and pulse the leg up, 80 to 100 times. Repeat with other leg.

FLEX & POINT
Holding the chair for balance, extend one leg to the side, foot flexed. Then point your toe and lift your leg as high as you can; flex your foot on the way down. Do 80 to 100 times; switch.

30s
At this age, "the abs naturally start to separate"; to fight that, try:

DOUBLE-ATTITUDE LIFT
Lie on your back with your legs out in front of you, crossed at the ankles. Do a crunch—but at the same time lift one of your legs (it can be slightly bent) to 90 degrees; holding this position, lift the other leg to 90 degrees. Slowly release the crunch while lowering legs; do 80 to 100 reps.

ADVANCED PIKING
Lie on your back, legs flat and arms overhead, hands holding a dumbbell. As you lift your upper body, raise your legs to 90 degrees, touching the weight to your shins. Lower slowly; repeat 80 to 100 times.

40s
As muscles start to weaken, Anderson says to target arms:

ARM CIRCLES
Stand with feet at shoulder width and extend arms to the sides at shoulder height. Keeping shoulders down, do 40 small arm circles going backwards, then 40 circling forward.

ARM LIFTS
Lie facedown on a mat with arms straight out to the side like a "T" and palms up. Spread fingers and lift arms up as high as you can, then lower; repeat 80 to 100 times.

HIGH "V" SHOULDER TOUCH
Stand with feet at shoulder width, a weight in each hand. Take straight arms up to a high "V," then lower to shoulder level; repeat 80 to 100 times.

50s
The key now? Cardio, for a healthy heart and a healthy weight:

WHOLE BODY BLAST
Do a variety of exercises from each age group at left.

CARDIO SHUFFLE
Create a 30-minute playlist (or try Anderson's workout mix, below). Using the music as a guide, do the following for one full song each: skip, walk at a fast pace, gallop, step-hop-step and then, finally, step with a knee lift and a small jump forward.

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