I've been able to get myself up and motivated to exercise more regularly lately, due in no small part to a fun website called Fitocracy. I have a few friends on the site and we manage to keep each other motivated via positive messages and, yes, maybe a little friendly and supportive competition.
But today I read an interview (at Fitocracy) with someone and when she was asked how she motivates herself, she said (basically) that it wasn't motivation. It's just what she does. Just like brushing your teeth or going to work every day, it's what "mature" adults do.
And that really struck a chord with me because I've often felt that way. When I was in my 20s and living in a house with 10 other people it was very easy to blow off work, or bills, or whatever else seemed boring or difficult. But then I took some night classes and got a second job. Everyone else at the house was asking how I motivated myself. I didn't realize it at the time, but it became more than motivation. It was just something I did.
So, does this mean I'll wake up and do crunches and push ups and ride the exercise bike every day? Nope. But I think I'm moving from being motivated to keep in better shape (for my family as well as myself) to it just being something I do.