As long as you smile, have sparkly eyes and stick your shoulders back, nobody's going to notice your bum or your waist or your feet, for that matter.
It is only necessary to have courage, for strength without self-confidence is useless.
The best preparation for acting is life - observing life and people and observing yourself. All that becomes your library. So when you have to research a part, a scene or an emotion, you go into the library and get what you need.