Some of my favorites:

For dealing with attitude:

"Experience is not what happens to you. It is what you do with what happens to you."

     Aldous Huxley

On teaching:

"I cannot teach anybody anything, I can only make them think."

     Socrates

On learning:

"What a child can do today with assistance, she will be able to do by herself tomorrow"

     Vygotsky....I like this one because I am also a special educator.....

For motivating teams:

"Only the mediocre are always at their best."

     Somerset Maughan

  "Gold there is, and rubies in abundance, but lips that speak knowledge are a rare jewel."

Proverbs 20:15 New International Version

You cannot escape the responsibility of tommorrow by evading it today.

Abraham Lincoln

ANYWAY

People are unreasonable, illogical and self-centered.

Love them anyway.

If you do good, people will accuse you of selfish ulterior motives.

Do good anyway.

If you are successful, you win false friends and true enemies.

Succeed Anyway.

The good you do today will be forgotten tomorrow.

Do good anyway.

Honesty and frankness make you vulnerable.

Be honest and frank anyway.

What you spend years building may be destroyed overnight.

Build anyway.

People really need help but may attack you if you help them.

Help people anyway.

Give the world the best you have and you'll get kicked in the teeth.

Give the world the best you've got ANYWAY.