If you think the world's problems are so big that you can't make a difference, don't be intimidated or deterred. One person can change the world. When I began writing this post I wanted to include a few examples, but rather than going with Martin Luther King Jr., Mahatma Ghandi, and others you already know about, I decided to focus instead on a few people who are less well known but nevertheless are having a real impact on making the world a better place. Wangari Maathai started a movement that has already planted 30 million trees in Kenya. Recent Nobel Peace Prize winner Muhammad Yunus has helped millions out of poverty with microcredit, very small loans to entrepreneurs too poor to qualify for traditional bank loans. Mikkel Frandsen is trying to make clean drinking water accessible to the billion people on the planet who don't have it. And Norman Borlaug has already saved about a billion people from starvation. Admittedly these are special people, in terms of both their commitment to their causes and their abilities to effect change. But even if you can't do it all yourself, there are plenty of problems for which every step toward a solution is itself enormously worthwhile. If you can't end the suffering of a million people, aim for a thousand, or even a hundred. As Edmund Burke said, "The only thing necessary for the triumph of evil is for good men to do nothing." If you want to change the world for the better but don't know where to start, let me suggest Darfur.