I love good quotes, ones that me think and take a look at myself. After each of the following I offer a comment.
"One should not torture himself over a single mistake. What is essential is one's presence of mind hereafter. When one makes a mistake, he should not be hesitant to correct it. Making a mistake and not correcting it, this is the real mistake."
Evaluate and re-evaluate, be introspective. I hear athletes repeatedly asking why they are not seeing improvement in their performances. There's a reason for this.
"Do all things with patience."
The impatient athlete tends to be a self-defeating one. Cerutty correctly said that impatience is evidence of a certain degree of immaturity.
"Be master of mind rather than mastered by mind."
For most of us that takes awareness of how we are and the desire to acquire mastery over ourselves. Again, being introspective is the key.
"We do not rise to the level of our expectations. We fall to the level of our training."
The simple truth.