The yoga mudra may be considered the queen of all postures in that it gives the benefit of five categories of effects. To make the complete yoga mudra one must be able to sit in the lotus position with the legs crossed and the left ankle on the right thigh and the right ankle on the left thigh. (In the beginning, however, you may make the posture with only one ankle up and then repeat with the other ankle up. Or if that is difficult, just cross your legs naturally).
With your arms locked behind you and the spine straight, begin to exhale and come forward towards the floor. If possible, let the head rest on the floor while the abdomen is pressing into the crossed legs. Contract your abdomen and settle yourself down onto your legs and relax in this position. If you would like to really relax, you may release your arms and just let them rest on the floor behind you.
This posture is also a meditation in itself. You will receive great benefit if you can keep your mind on your body.
Contraindications: Serious lower back problems, High blood pressure, detached retina