It's paramount we take ownership of our lives. Sadness is greatly due to our having sacrificed ourselves over to a power outside of ourselves. We need to be proactive in creating positive thoughts and actions that will align ourselves with where we want to be and what we want to feel in life.
Always remember, child... that to think bad thoughts is really the easiest thing in the world. If you leave your mind to itself it will spiral you down into ever increasing unhappiness. To think good thoughts, however, requires effort. This is one onf the things that discipline - training - is about.
He felt the guilt of inaction, of simply waiting while his life went to waste. No one was worth the gift of his life, no one could possibly be worth that. It belonged to him alone, and he did not deserve it either, because he was letting it waste. It was getting away from him and he made no effort to stop it. He did not know how.