DanAllan.com

1. Make a fist around two fingers (borrowed from someone else’s hand) and squeeze hard for half a minute or more. Then relax your fist, but don’t open it. Delicately slip the fingers out, and then gently try to open your fist. What does it feel like?
2. Stand in a doorway. Push your arms outward, pressing the backs of your hands into the doorframe, hard. Do this for at least half a minute. Then step out of the door, relaxing your arms and shoulders. What happens?
3. Lie on the floor on your back. With your legs straight (knees locked!) have a friend raise one leg and press gently so the leg muscle is stretched. It should be a little uncomfortable (and definitely a little weird) but not painful. Pause for at least half a minute. Close your eyes while your friend lowers your foot slowly back to the ground, holding by the toe. What does it feel like?

The first one in particular is good for moments when you are waiting around or standing in line with a friend. If you know more of these, post them in the comments!