"First with the head, then with the heart, you'll be ahead from the start."
- From the book The Power of One by Bryce Courtenay
If at some point you find that you have lost faith in your ability to do what you want in life, I recommend reading The Power of One by the South African-Australian author Bryce Courtenay (1).
The book follows the story of a young boy, nicknamed Peekay, as he grows up in South Africa from 1939 to 1951 (don't worry, I won't give the story away if you haven't read the book yet). In this story, Peekay learns that the mind is the true athlete within any person; the body is simply the means by which the mind runs faster, jumps higher, kicks better, swims harder, or boxes better.
Peekay applies this fact to boxing through the motto, "First with the head, then with the heart," in which the head is defined as the devised plan or strategy to achieve a goal whereas the heart is defined as the implemented grit or resolve needed to carry it out. Applying this to boxing, Peekay learns that winning is done by devising a plan to defeat a particular opponent, followed by implementing the grit to carry it out. Doing this in the reverse sequence doesn't work; passionately swinging away at an opponent without thinking ahead results in defeat.