The mind is incredible. Once you've gained mastery over it, channeling its powers positively for your purposes, you can do anything. I mean anything. The secret is to make your mind work for you not against you. This means constantly being positive. Constantly setting up challenges you can meet either today, next week, or next month. "I can't..." should be permanently stricken from your vocabulary, especially the vocabulary of your thoughts. You must see yourself always growing and improving.