image from www.pinklotus.org

Sat Kriya is a fundamental posture that provides great benefits in as little as three minutes a day. Spinal alignment, pranayama and chanting come together to channel, focus, and redistribute your energies. 

To practice Sat Kriya, sit on your heels (Vajrasana) and raise your arms above your head, elbows hugging your ears and hands in Jupiter mudra (fingers interlocked, index fingers extended and joined. left thumb over right for ladies, right over left for men) or prayer mudra (after some experience is built). Begin chanting Sat Nam in a steady rhythm. 

As you chant SAT, flex your belly toward your spine from the navel and solar plexus. As you chant NAM, relax your belly. Don't worry about controlling your breath - it will come to you naturally. Continue to chant and flex your belly, stimulating the flow of energy from the lower chakras into the rest of your body. Visualize Kundalini awakening, uncoiling, and rising through your spine and channeling pooled energy toward healing, creativity, and light.

It is recommended to rest for at least twice as long as you practiced the kriya. A three minute practice is powerful, and can very slowly be built up to 31 minutes, followed by a long, deep relaxation period. A recommended slow buildup from Sadhana Guidelines is to practice Sat Kriya for 3 minutes, then rest for 2 minutes. Continue until you have done the kriya for 15 minutes, and rested for 10, then finish your relaxation with another 15-20 minutes of rest. Don't push it out of ego - slowly building up is essential. This exercise not only stimulates the flow of energy, but the function of all internal organs and the flow of blood through the heart and lungs. 

"Let the kriya prepare the ground of your body properly to plant the seed of higher experience. It is not just an exercise, it is a kriya that works on all levels of your being - known and unknown. You might block the more subtle experiences of higher energies by pushing the physical body too much. You could have a huge rush of energy. You may have an experience of higher consciousness, but not be able to integrate the experience into your psyche. So prepare yourself with constancy, patience and moderation. The end result is assured."

From Sadhana Guidelines, Gurucharan Singh Khalsa
http://www.yogatech.com/Gurucharan_Singh