Are we scared to go beyond our limitations?

An elephant, when young, is tied with a length of rope to keep it from escaping. After struggling for a while with this, the elephant soon learns that it can't break free. But even years later, when the elephant has reached massive size, it still won't fight against the same thin rope, even though it could easily snap it with just a tug. It has learned its limitation so well that it no longer tries.