Shakti Mudra forms by clenching fists of both the hands. The practice of this mudra can be done by sitting in any asana what you wish.
A person, who is physically weak, should do the practice of this mudra because the regular practice of mudra can bring new energy in him. This mudra ends the problem of body shivering forever. The face of the person appears healthy.
This mudra is very useful for the players or people who are interested in games.