Like I said in another post.
My kids keep me motivated. Can't quit because little eyes are watching. What will they think about me if I do? This mommy is no quitter.
I stay motivated by keeping my eyes on the prize I remind myself why it is I workout in the first place.
I use lots of different things. Family, friends, tracking progress. I also find music to be a huge help! My the beats are loud I know I go harder than I would be able to without it.