If you put fleas in a shallow container they jump out. But if you put a lid on the container for just a short time, they hit the lid trying to escape and learn quickly not to jump so high. They give up their quest for freedom. After the lid is removed, the fleas remain imprisond by their own self policing. So it is with life. Most of us let our own fears or the impositions of others imprison us in a world of low expectations.