Then we learn how to sit for prayer

How to sit in prayer? There is no real prescription what the best would be, unless you belong to a specific religious tradition. Bringing the hands together, or only the palms, is the most usual, and to do this while sitting or standing. By using the same body position every time while in prayer, the body and mind start to remember this. That is why after a time when one closes the hands in prayer it is as if one starts already unconsciously to pray.

http://www.spirithome.com/prayer-positions.html