"The greatest discovery of all time is that a person can change his future by merely changing his attitude."

"Any man who thinks he can be happy and prosperous by sitting at a desk and letting others do the work for him is doomed to failure."

"There can be no great success without great resistance."

"There is no joy in work without application."

"I have not been able to discover that anyone knows enough to say what is and what is not possible."