A jug fills drop by drop
— Buddha
If you want others to be happy, practice compassion; if you want yourself to be happy, practice compassion.
— Dalai Lama

The Commitment - 5% of income to charity and/or 75 hours of community service.  Some small kindness daily. 

Researchers have shown that giving back and being kind can increase our level of well being and happiness.  In one example, a group of students was asked to perform five random acts of kindness per week for six weeks.  At the end of the test, these students were happier than a control group. Giving back is a win-win proposition.

I have been appallingly bad at giving back thus far in my life.  I am kind enough day to day with friends, family and strangers, but I've done minimal charity or volunteer work, and have never given more than 3-4% of my income to charity. The pledge is a perfect opportunity for me to change.  I have not yet decided where I will donate my dollars and hours, but here are a few options that appeal to me: