I always thought I could play ...

I always thought I could play pro ball. I had confidence in my ability, You have to. If you don't who will?
 Johnny Unitas

Quotes from the same author

In order to be successful at anything you choose to do, you must make a 100 percent commitment to what it is you are trying to do. If you put 50 percent of your ability into it, that is all that you will get out of it. You must discipline your body and your mind to work towards the goals you have set. Once you have made this decision, then the work begins.
 Johnny Unitas
There is a difference between conceit and confidence. Conceit is bragging about yourself. Confidence means you believe you can get the job done.
 Johnny Unitas