I liked a couple from D.Trump "Keep frustration as a motivator" and "Don`t count on happenstance to get you anywhere,because it won`t"
It's not strictly a business speech, but it's my favorite motivational one. Christopher Walken in Poolhall Junkies: https://www.youtube.com/watch?v=jzekDivpK3M&feature=youtube_gdata_player