"Failure is not about insecurity. It's about lack of execution." -- Jeffrey Gitomer  

"Challenges make you discover things about yourself that you never really knew. They're what make the instrument stretch—what makes you go beyond the norm." –- Cicely Tyson  

"A feeling of confidence and personal power comes from facing challenges and overcoming them." -– Brian Tracy

"Great spirits have always encountered violent opposition from mediocre minds." -- Albert Einstein  

"The most rewarding things you do in life are often the ones that look like they cannot be done." -- Arnold Palmer  

"Problems are only opportunities in work clothes."-- Henry J. Kaiser  

"When you've got something to prove, there's nothing greater than a challenge." -- Terry Bradshaw

"There aren't any great men. There are just great challenges that ordinary men like you and me are forced by circumstances to meet." -- William F. Halsey  

"I will say this for adversity: people seem to be able to stand it, and that is more than I can say for prosperity." -- Kim Hubbard  

"All progress is precarious, and the solution of one problem brings us face to face with another problem." -- Martin Luther King, Jr.

"When we long for life without difficulties, remind us that oaks grow strong in contrary winds and diamonds are made under pressure." -- Peter Marshal  

"Prosperity discovers vice, adversity discovers virtue." -- Francis Bacon  

"Strength does not come from winning. Your struggles develop your strengths. When you go through hardships and decide not to surrender, that is strength." -- Arnold Schwarzenegger  

"The walking of Man is falling forwards." -- Ralph Waldo Emerson  

"Do not worry about your difficulties in mathematics. I can assure you mine are still greater." -- Albert Einstein  

"Fortunately, problems are an everyday part of our life. Consider this: If there were no problems, most of us would be unemployed. Realistically, the more problems we have and the larger they are, the greater our value to our employer." -- Zig Ziglar