They can because they think they can.
Virgil

I am the greatest!
Muhammad Ali

Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure. It is our light, not our darkness, that most frightens us. We ask ourselves, who am I to be brilliant, gorgeous, talented, and fabulous? Actually, who are you not to be? You are a child of God. Your playing small doesn't serve the world. There's nothing enlightened about shrinking so that other people won't feel insecure around you. We are all meant to shine, as children do. We are born to make manifest the glory of God that is within us. It's not just in some of us, it's in everyone. And as we let our own light shine, we unconsciously give other people permission to do the same. As we are liberated from our own fear, our presence automatically liberates others.
Marianne Williamson

Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson

We are what we repeatedly do. Excellence, therefore, is not an act but a habit.
Aristotle

We are what we think.
Buddha

Our greatest glory is not in never falling but in rising every time we fall.
Confucius

Victory belongs to the most persevering.
Napoleon

It's not the size of the dog in the fight, but the size of the fight in the dog.
Mark Twain

It's never too late to be what you might have been.
George Eliot

We tend to get what we expect.
Norman Vincent Peale

This world is but canvas to our imaginations.
Henry David Thoreau

No-one can make you feel inferior without your consent.
Eleanor Roosavelt

Nothing will ever be attempted if all possible objections must first be overcome.
Samuel Jackson

The harder you work, the harder it is to surrender.
Vince Lombardi

Whether you think you can or think you can't, you are right.
Henry Ford

Every artist was first an amateur.
Ralph Waldo Emerson

The power of imagination makes us infinite.
John Muir

We become what we think about all day long.
Ralph Waldo Emerson

Life is either a daring adventure or nothing.
Helen Keller

The man of wisdom is never of two minds; the man of benevolence never worries; the man of courage is never afraid.
Confucius

Happiness resides not in possessions and not in gold; the feeling of happiness dwells in the soul.
Democritus

The greatest mistake you can make in life is to continually be afraid you will make one.
Elbert Hubbard

Do not wait for your ship to come in - swim out to it
Author Unknown

There are no secrets to success. It is the result of preparation, hard work, learning from failure.
Colin Powell

This above all: to thine own self be true, and it must follow, as the night of the day, thou canst not then be false to any man.
William Shakespeare

Good, better, best. Never let it rest. Until your good is better and your better is best.
Tim Duncan

Everybody pulls for David, nobody roots for Goliath.
Wilt Chamberlain

Things that hurt, instruct.
Benjamin Franklin

To lose patience is to lose the battle.
Mahatma Gandhi

Most of the shadows of this life are caused by our standing in our own sunshine.
Ralph Waldo Emerson

Do not anticipate trouble, or worry about what may never happen. Keep in the sunlight.
Benjamin Franklin

I never think of the future - it comes soon enough.
Albert Einstein

It is the trouble that never comes that causes the loss of sleep.
Charles Austin Bates

Worry often gives a small thing a big shadow.
Swedish Proverb

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

If you can imagine it, you can achieve it; if you can dream it, you can become it.
William Arthur Ward

Nothing great was ever achieved without enthusiasm.
Ralph Waldo Emerson

We are still masters of our fate. We are still captains of our souls.
Winston Churchill

Imagination is more important than knowledge.
Albert Einstein

Every problem has in it the seeds of its own solution. If you don't have any problems, you don't have any seeds
Norman Vincent Peale

One who fears failure limits his activities. Failure is only the opportunity to more intelligently begin again.
Henry Ford

In the middle of difficulty lies opportunity.
Albert Einstein

Ask yourself this question: "Will this matter a year from now?"
Richard Carlson
Writing in Don't Sweat the Small Stuff.

It's not the situation…… it's your reaction to the situation.
Bob Conklin

The harder the conflict, the more glorious the triumph.
Thomas Paine