What does one believe in?
There are probably hundreds of little belief's that fit within your life. It could start as something simple like "No limits" perhaps even something creative like "Don't be a Dick". Religion, upbringing, media, and books help form the basic parts but it is self discovery that should lead you to your own creed. In the journey through life not many ask what you believe and it is usually only actions that speak it. Sometimes actions are screaming it to the world and other times it is a whisper. What hinders it is self deception. We so want to be better than what we are or at least believe we are better than what we are that self deception blocks us from attaining our goal. Perhaps the best credo/creed could simply be, "honesty and know thy self".