Self pity is the only thing that holds you back

I saw a three legged dog today. She had pups... she was hobbling along searching for food. Her situation brought tears in my eyes... but she had to do what she had to do. She had to survive... she could not afford self-pity. Why cant we think in the same way when we are not in such a terrible situation. Why cant we stop wasting time and do what really has to be done? Why should we wait for such adversities before we act?