(Disclaimer: Part of my quote-gathering project involved correctly attributing quotes, which is quite a problem on the internet. I have not gone to any lengths to check the attributions on the following quotes. Knowing the true author sometimes makes the quote more meaningful, but usually the words speak for themselves.)
There is only one group of people who don't have problems and they're all dead. Problems are a sign of life. So the more problems you have, the more alive you are.
-- Norman Vincent Peale
Affliction comes to us, not to make us sad but sober, not to make us sorry but wise.
-- Henry Ward Beecher
The creation of art is not the fulfillment of a need but the creation of a need. The world never needed Beethoven's Fifth Symphony until he created it. Now we could not live without it.
-- Louis I. Kahn
There is no baser folly than the infatuation that looks upon the transient as if it were everlasting.
For one word a man is often declared to be wise, and for one word he can be judged to be foolish. We should be careful indeed what we say.
A good leader is a person who takes a little more than his share of the blame and a little less than his share of the credit.
-- John C. Maxwell
Why should we worry about what others think of us? Do we have more confidence in their opinions than we do in our own?
-- Brigham Young
Study as if you were going to live forever; live as if you were going to die tomorrow.
-- Maria Mitchell