Just as it sounds, with your arm extended and your thumb on the outside of your fingers, make a typical fist. It may sound easy, but the goal is to start small with an almost loose fist, and then work your way up in firmness. It is also important to try and hold the fist in that position for at least 10-15 seconds. If that is too long to hold without experiencing pain, start with a looser grip and hold for less time until you can make it 10 seconds. This exercise improves flexibility, strengthens the finger muscles, and promotes healthy blood flow in the hands. Not to mention, you can pretty much do this exercise whenever and wherever you want.