Better get a stiff neck from aiming too high than a hunch from aiming too low. Failure should be our teacher, not our undertaker. Failure is delay, not defeat. It is a temporary detour, not a dead end. Failure is something we can avoid only by saying nothing, doing nothing, and being nothing. One cannot govern with buts. You cannot pick cherries with your back to the tree. You do not have to be a fantastic hero to do certain things, to compete. You can be just an ordinary chap, sufficiently motivated to reach challenging goals.
The difference between doers and dreamers is that the latter wait for the mood before taking action while the former create the mood by acting. Success or failure depends more upon attitude than upon capacity. Successful people act as though they have accomplished or are enjoying something. Soon it becomes a reality. Act, look, feel successful, conduct yourself accordingly, and you will be amazed at the positive results. Nothing of great value in life comes easily.