Don't think you can, know you can

If you've ever seen "The Matrix" you probably remember Neo's training. Morpheus is constantly repeating the phrase "don't think, know. " Neo followed his advice and he did what at first was impossible, landed a hit on Morpheus. This applies to our own self improvement as well. Don't think you can run 5 miles, don't think you can bench 300 lbs, don't think you can shatter bricks, know you can. Of course a little bit later in the movie Neo has to jump from one building to another 50 stories up above a busy street, and he fails. Sometimes no amount of belief can make you succeed, so you must train that much harder.