Don't let anyone take away your voice. This doesn't mean there isn't a time and place, but your feelings are valid. Let me repeat that: Your feelings are valid.
Those moments when your whole mind and body want to say yes, but you say 'no' instead? STOP IT. My most vivid memories and best moments in life, my accomplishments, have come from saying 'yes' instead.
Get in a fake fighting match with a friend in a department store. Watch how no one will say anything, but the crowd draws. Learn to always say something.
Once, when I was little, I pretended with a friend that an inflatable raft was actually on a river in the Amazon. This is still fun to do.
Play laser tag at least once a month. No mercy for children.
Walk up to a stranger and tell them how everything is going to be okay, and then walk away. Alternatively, walk up to a stranger and tell how you fought on whether or not to steal an item they are carrying, then walk away. Do this in a crowd so they can't pinpoint you later.
Write a love letter to yourself. Hide it in an odd place to find later.
Lose your keys. Lose your wallet. Lose your purse, your cell phone, your car... Priorities and important things become clear when you lose.
Skydive. Then, you can do anything.
Share. With everyone. It is so liberating and you become closer with people who you are meant to be with. Just make sure to listen, too.
If you think you can't do it, you can. People are capable of anything, from murder to going to the moon.
(quick writing from a retreat)