Peter Tatchell guiding motto is:

Don't accept the world as it is, dream of what the world could be, and then help make it happen.

Featured on BBC Radio 4 Midweek on 25 January 2012.

Maybe it's because I had Peter's quote in my mind that I spotted this quote from Eleanor Roosevelt:

When you have decided what you believe, what you feel must be done, have the courage to stand alone and be counted.