I think you have to really find what exercise is your passion. If it's something you don't really enjoy or look forward to, you aren't going to stick with it. I found my passion in cycling - 7 bikes and a lot of miles on the road. I look forward to riding more than almost anything else in my life, and I'm always thinking ahead to "when can I ride" and "where can I ride". For me, it's a big adventure as well as exercise, I like to push my limits and see how far I can, and how fast.