A favorite photographer of mine, Keith Carter, has many quotes written on the walls of his darkroom and this particular quote stands out to me:

Press On

"Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education alone will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent."

--Calvin Coolidge