I found that reading biographies or memoirs of people I admire (or even people I never heard of) is very motivational. Although we see other people's successes as coming easily, in most cases people overcame obstacles, rose above bad situations, and worked very hard for their successes. Recently I've been reading about our founding fathers & have been inspired by their stories. One of the best memoirs I've read recently was.. (cllick title for more info)
.."The Glass Castle" by Jeannette Walls, who grew up with neglectful, incompetent parents, yet she & her siblings overcame their poor beginnings with hard work to become successful & productive adults. It has been months since I read that book, but it has stuck with me. I think about it daily.