Have you ever watched a cat stretch his back? He rounds and arches high, showing off a dual gift of spinal strength and flexibility. "Joseph Pilates marveled at cats," says Pilates instructor Mary Bowen, who studied with the fitness legend himself. "Our feline friends inspired the Pilates method we know today."

The following exercises target the spine and its supporting muscle groups. (If you're experiencing back pain or have osteoporosis, consult your health-care practitioner before doing this routine.) Over time, you'll find that the effort you invest today will prevent aches and pains -- and keep you nimble -- going forward.

What it does: Stretches the lower-, middle-, and upper-back muscles; stretches the spine; strengthens the abdominal muscles.

How to do it: Sit on the floor, knees bent, abs drawn in, shoulders pressing down, hands on the floor slightly behind you for support. Cross your right ankle over the left, bring both feet up off the floor, and balance on your sitting bones; gently hold the left foot with the right hand and the right foot with the left hand. Inhale, and roll back to your shoulders (be careful not to roll onto your head), curving your spine as you go. Exhale, and roll up to the starting position, but don't let your feet touch the floor. Repeat 10 times.

What it does: Strengthens the lower back and your core; tones the glutes and the thighs.

How to do it: Lie on your back with your knees bent and feet planted directly under the knees, hip-width apart. Rest arms by your sides. Without dropping the chin toward the chest, raise your hips off the ground as far as you can, forming a triangle. Shoulders stay on the mat. Lift your left leg up so that it's completely vertical (perpendicular to the floor) with toes pointed; this is the starting position. Keeping your hips stationary and leg straight, inhale as you bring the left leg down to hip height (parallel to the floor), then exhale and return it to vertical. Repeat 10 times on the left leg, then switch legs and do 10 reps on the right. Complete the entire sequence again, left and right legs, for a total of 20 reps on each side.

What it does: Focuses on the abs, working all the muscles; strengthens the psoas muscle (connects the lower spine to the hip).

How to do it: Lie on your back with knees in toward the chest, head and shoulders lifted off the floor, and arms reaching forward. Keeping the belly pulled in, inhale and, like a snow angel, sweep the arms out and up into a wide "V," simultaneously extending the legs straight out to about a 45-degree angle. Continuing to move fluidly, exhale and bring the legs and arms back to the starting position. Repeat 10 times.

What it does: Releases tension in the lower back; strengthens and stretches the obliques.

How to do it: Sit upright on your mat with your left leg bent in front of the pelvis and the other leg bent to the side. Extend both arms out like airplane wings, keeping shoulders down and back. The spine is straight. Exhale and cartwheel the arms down to the left until both palms are flat on the ground and shoulders are parallel to the floor. Go as close to the floor as possible without disturbing your lower body's placement. Hold for one inhale, then reverse the movement on the next exhale, returning to the starting position. Move with fluidity and control from start to finish. Repeat 10 times, switch leg position, and perform 10 times to the right.

What it does: Strengthens muscles in the lower, middle, and upper back and improves posture.

How to do it: Lie facedown, with your belly on the mat, legs stretched behind you, hip-width apart. Contract your abs to lift your navel in toward your spine, and stretch your arms overhead with both palms facing the floor. This is the starting position. Exhale as you lift your right leg and left arm up and away from the floor; lift your limbs as high as you can without bending at the elbow or knee. Inhale as you switch the legs and arms, reaching the left leg and right arm up as you lower the right leg and left arm. This is one repetition. "Swim" for 30 fast-paced repetitions and release.

What it does: Releases tension from the back and engages the abs.

How to do it: Stand upright with feet planted approximately 6 inches apart, toes pointing straight ahead, and arms extended overhead. From start to finish, your abdominals should control this movement. Keeping your arms parallel to your ears, bring the chin toward the chest, and begin to slowly roll your spine down, vertebra by vertebra. Roll down as far as you can go and, if you feel pain or too much tension in your hamstrings, bend your knees as needed. Now roll up in the reverse order, returning to the starting position. Repeat 5 times.