If you have something to give, don't wait. Every act of generosity matters regardless of how small you might think it. "A Life Lesson from a Volunteer Firefighter" is a 4 minute TEDtalk by Mark Bezos.
It's not about you; its about the change you encourage. "How to Start a Movement" is a cool video explanation about leadership from a 2010 TEDtalk by Derek Sivers.