“Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.”
Like most quotations attributed to Mark Twain, Albert Einstein, etc., this was not actually said by him. See http://quoteinvestigator.com/2011/09/29/you-did/ for a bit more information; it seems actually to be from the mother of someone called H Jackson Brown Jr., who published a book of Things His Mom Said.
“Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.”