What Can You Do?

Former UCLA basketball coach John Wooden passed away at the age of 99 in early June of 2010. Columnist Michael Wilbon shared some of his favorite Wooden quotes in his column a couple of days after his death:

The main ingredient of stardom is the rest of the team.

Nothing will work unless you do.

Do not let what you cannot do interfere with what you can do.

The [person] that says something cannot be done should never interrupt the one who is doing it.
Wooden was very successful as a high school and college coach who spoke the above in relation to athletes or sports but most would say they are applicable to many situations in life.

What prevents a person from saying "I can’t" when faced with seemingly insurmountable obstacles? What helps you try again when you have already failed once or multiple times?