Kurmasana, Turtle pose, requires very flexible hip flexors, hamstrings and lower back and should only be attempted when you are thoroughly warmed up. It is an intense, introspective pose that withdraws the senses from outside stimulation, slows an agitated nervous system, calms the mind, tones the spine and the abdominal organs, and increases hip flexibility as it lengthens the spine. Learn it first under the guidance of a certified yoga teacher who can supply you with a safe warm-up sequence and correct your posture to prevent injury.
Sit on your yoga mat in Dandasana, or Staff pose, stretching your straight spine toward the ceiling and relaxing your legs in front of you, feet naturally flexed.
Spread your legs a little more than shoulder-width, so your heels are close to the edge of the mat.
Raise your tummy away from your hip bones so you are sitting tall as you fold your torso over your thighs, allowing your knees to bend slightly.
Slip your arms, palms down, under your knees and walk arms out to the sides as you deepen your forward bend.
Expand your chest, imagining a stretch that widens it from side to side, and release all tension in your shoulders so they relax toward the floor and away from your ears. Breathe evenly and slowly, allowing your muscles to relax at their own pace. Don't force anything.
Turn your legs so the knees and toes are pointing toward the ceiling but keep your palms flat on the floor. Walk your arms wider and toward your back to deepen the stretch, lower your back and elongate your torso. As you breathe in, bring your chin and upper chest forward. As you breathe out, lengthen your legs, sliding your heels along the floor.
Touch your forehead to the floor, if you can. Eventually, as you become more flexible, you may be able to lay your chin and chest on the floor without strain and move your arms back further behind you. Breathe evenly in Turtle pose for 15 to 30 seconds.
Bend your knees and lift your torso to slowly come out of the pose and return to Dandasana.