The first requisite of ...

The first requisite of success is the ability to apply your physical and mental energies to one problem without growing weary.
The first requisite of success is the ability to apply your physical and mental energies to one problem without growing weary.

More phrases

Effort only fully releases its reward after a person refuses to quit.
Never complain and never explain.
A good plan violently executed now is better than a perfect plan executed next week.
 George S. Patton
Problems are not stop signs, they are guidelines.
 Robert Schuller
Never give up, for that is just the place and time that the tide will turn.
 Harriet Beecher Stowe

Quotes from the same author

The memory of my mother will always be a blessing to me.
My mother was the making of me.
My mother was the making of me. She was so true and so sure of me, I felt that I had someone to live for - someone I must not disappoint. The memory of my mother will always be a blessing to me.
I am long on ideas, but short on time. I expect to live to be only about a hundred.
There will one day spring from the brain of science a machine or force so fearful in its potentialities, so absolutely terrifying, that even man, the fighter, who will dare torture and death in order to inflict torture and death, will be appalled, and so abandon war forever.