First Degree: Lay on floor with feet under heavy furniture (to just past the toes). Knees are bent, relax the neck, back and shoulders. INHALE, and just after you begin to EXHALE, lift your upper body to the seated position using your abdominals. This should be a slow, smooth motion with no pause at the top. INHALE again as you lower the body back down. EXHALE again in the rest position. Do 6 of these, moving up to 12 over a few weeks.
N.B. Do not roll the body up; do not draw in the abdomen. Rather, distend the abdominal muscle between your knees when in the seated position. Hands can be used to support lifting and lowering, as they lie beside the body, hands flat on the floor.
Second Degree: As above, but with hands on hips. May alternatively use a stool or raised object to offer increased range of motion. There should be no pause in the motion at this degree. Begin EXHALATION part way through the lowering body phase, and through the lifting phase.
Third Degree: As above, but with hands behind neck and head.
Fourth Degree: As above but with hands fully outstretched above head (arms locked to ears).

(excerpt from fan summary)

sit ups