"Trust in God, but tie your camel first."
From Islam - not directly from the Koran but one of the quotes and stories about Mohamed that were collected later. I also like the Boddhisatva vows from Buddhism:
Sentient beings are numberless, I vow to save them all.
Evil desires are inexhaustible, I vow to extinguish them all.
The teachings are innumerable, I vow to learn them all.
The way of the Bodhisattva is unattainable, I vow to attain it.
The first line, especialy, always gives me a thrill. Sometimes when I'm tired and discouraged, I repeat it to myself, and it always gives me a renewed sense of determination. I guess I'm a little qixotic
