Burning desire to be or do something gives us staying power - a reason to get up every morning or to pick ourselves up and start in again after a disappointment.
Life's up and downs provide windows of opportunity to determine your values and goals. Think of using all obstacles as stepping stones to build the life you want.
To find in ourselves what makes life worth living is risky business, for it means that once we know we must seek it. It also means that without it life will be valueless.