Wouldn't it be great if it was truly addictive? My fiance was telling me it takes about three weeks to form a habit, but I told him that you always have to keep pushing yourself to exercise, because quitting isn't hard to do. All it takes is skipping a day here, a day there, then next thing you know you're skipping a week, and then it's all over. I stopped exercising during my second pregnancy, and never picked it up again until now, over four years later. I don't know how I even made it the one year that I did exercise, because before that I had never lasted longer than a month or two. After going a year straight, I know I can keep it up if I just set my mind to it. And if I get pregnant again, I'll make sure to buy lots of prenatal exercise videos, lol.