"When you're feeling good and feel like you can't miss, it's a good feeling, " said Williams, who shot 11 of 18 in the second half at one of his favorite arenas.

WSJ: Lopez, Williams lead Nets past Mavericks 113-96

Every time I have the chance to go on court and play well, feel competitive, is a really good feeling.

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These findings would not have surprised Charles Darwin, who in addition to theorizing on evolution in The Origin of the Species, also developed the Facial Feedback Response Theory, which suggests that the act of smiling actually makes us feel better (rather than smiling being merely a result of feeling good).

FORBES: The Untapped Power Of Smiling

"I think the overriding feeling that we have, all of us, is just to make people feel good, " Peter says.

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In other words, a benefit concert gives the celebrities the feeling that they are using their particular skills to do something good, and it makes donors feel good because they become a part of a bigger pool of giving.

FORBES: Sometimes celebrities are the best people to rally donors.