I'm one of those folks who keeps starting and stopping. I actually got started with real weight lifting when I joined a local CrossFit gym. I cannot remember working so hard and being so pleased with a fitness experience. Unfortunately at the time I was not eating clean. Then unemployment came and scrambling to keep my head above water. I have to say that in the past two years I have recovered nicely (found stable employment and started working on a Masters of Science in IT). So while other areas in my life have fallen into place, physical fitness had been ignored. Recently I've been pining for more positive changes in my life. I thought where else better to start than with my body!
At the very least, when the day doesn't go my way, I always feel like I've accomplished something. Of course there is the superficial - I want to look better, but deeper than that I think about my mother and all she has suffered with due to uncontrolled hypertension, diabetes, and dialysis. Its well in my power to avoid a similar future.