Speaking as a long-time runner, a veteran of many marathons and ultramarathons, currently preparing for my ninth 72-hour race, I'll verify that persons to whom an exercise program is most successful are not those who treat it as a necessary and mildly disagreeable obligation that has to somehow be worked in with everything else, in order to get out of the way and thereafter carry on with "real" life, but those for whom exercise is one of life's driving passions, in the same way that music, art, literature, and science (as examples) are to so many of us. I myself am such a person. When someone learns to love some particular pursuit, he will find a way to do it regularly.