Peter F. Drucker:

There is nothing so useless as doing efficiently that which should not be done at all.

Franklin D. Roosevelt:

Happiness is not in the mere possession of money; it lies in the joy of achievement, in the thrill of creative effort.

George Santayana:

Fanaticism consists of redoubling your effort when you have forgotten your aim.

Haitian proverb:

Beyond the mountains there are mountains again.

Helen Keller:

I long to accomplish a great and noble tasks, but it is my chief duty to accomplish humble tasks as though they were great and noble. The world is moved along, not only by the mighty shoves of its heroes, but also by the aggregate of the tiny pushes of each honest worker.

Henry David Thoreau:

There are a thousand hacking at the branches of evil to one who is striking at the root.

Herodotus:

Some give up their designs when they have almost reached the goal; while others, on the contrary, obtain a victory by exerting, at the last moment, more vigorous efforts than ever before.

Jane Addams:

Nothing could be worse than the fear that one had given up too soon, and left one unexpended effort that might have saved the world.

John Wesley:

Do all the good you can, by all the means you can, in all the ways you can, in all the places you can, at all the times you can, to all the people you can, as long as ever you can.

Lin Yutang:

Besides the noble art of getting things done, there is the noble art of leaving things undone. The wisdom of life consists in the elimination of non-essentials.

Marian Wright Edelman:

Whoever said anybody has a right to give up?

Oliver Wendell Holmes:

The mode by which the inevitable comes to pass is effort.

Theodore Roosevelt:

It is not the critic who counts, not the man who points out how the strong man stumbled, or where the doer of deeds could have done better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes short again and again, who knows the great enthusiasms, the great devotions, and spends himself in a worthy cause, who at best knows achievement and who at the worst if he fails at least fails while daring greatly so that his place shall never be with those cold and timid souls who know neither victory nor defeat.

From a speech given in Paris at the Sorbonne in 1910

Thomas Jefferson:

I'm a great believer in luck and I find the harder I work, the more I have of it.

Thomas Jefferson (attributed):

I'm a great believer in luck, and I find the harder I work the more I have of it.

Tom Lehrer:

Life is like a sewer. What you get out of it depends on what you put into it.

Vince Lombardi:

Leaders aren't born they are made. And they are made just like anything else, through hard work. And that's the price we'll have to pay to achieve that goal, or any goal.

Vince Lombardi:

Dictionary is the only place that success comes before work. Hard work is the price we must pay for success. I think you can accomplish anything if you're willing to pay the price.