Barack Obama
Making your mark on the world is hard. If it were easy, everybody would do it. But it's not. It takes patience, it takes commitment, and it comes with plenty of failure along the way. The real test is not whether you avoid this failure, because you won't. It's whether you let it harden or shame you into inaction, or whether you learn from it; whether you choose to persevere.
Henry Wadsworth Longfellow
Perseverance is a great element of success. If you only knock long enough and loud enough at the gate, you are sure to wake up somebody.
Orison Swett Marden
Success is the child of drudgery and perseverance. It cannot be coaxed or bribed; pay the price and it is yours.