Another motivating reason is that Bush loves his country and will be all possible to make it better then when he first took office. He's a true patriot that steps up to the plate.
Clinton and his friends bemoan the fact that he had no big issues to tackle or wars to fight. However, he could have done the same as Bush. The same problems were there, the same circumstances (even 9/11 could have been prevented), and the same rhetoric, except then the rhetoric was favorable to the President (Clinton). Even with all that support he was just too timid to act, frozen in fear of unfavorable polls.
Thank God for Bush.