Hm, have you considered enrolling in a community college class? I'm only suggesting this because I remember how when I was in college I took a jogging class that really helped me to get in shape. I stuck with it for the sole reason that it was a class, and this somehow gave me enough of a sense of urgency to show up every day and get used to it. Even though ideally one would be able to exercise of their own accord, signing up for a formal, graded school class can sometimes give you that extra motivation.