One of my favorite people to quote is Theodore Roosevelt. I know the man has his faults, but he could put words together in a way that demands enthusiasm and if you can find the right context to use his words - it is gold.
Here are two of my favorites:
“Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in that gray twilight that knows neither victory nor defeat.”
“It is not the critic who counts; not the man who points out how the strong man stumbled or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs and comes short again and again; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best, knows in the end the triumph of high achievement, and who, at the worst, if he fails, at least fails while daring greatly so that his place shall never be with those timid souls who know neither victory or defeat.”