"Optimism is the faith that leads to achievement "
Helen Keller

"Become a possibilitarian. No matter how dark things seem to be or actually are, raise your sights and see possibilities -- always see them, for they're always there."
Norman Vincent Peale

"We are all in the gutter, but some of us are looking at the stars." 
Oscar Wilde 

"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
Winston Churchill

"I am fundamentally an optimist. Whether that comes from nature or nurture, I cannot say. Part of being optimistic is keeping one's head pointed toward the sun, one's feet moving forward. There were many dark moments when my faith in humanity was sorely tested, but I would not and could not give myself up to despair. That way lays defeat and death." 
Nelson Mandela

"Be careful what you water your dreams with. Water them with worry and fear and you will produce weeds that choke the life from your dream. Water them with optimism and solutions and you will cultivate success. Always be on the lookout for ways to turn a problem into an opportunity for success. Always be on the lookout for ways to nurture your dream." 
Lao Tzu