I couldn't agree more. I was a part time fitness instructor for over 10 years, ate like crap but worked out intensely between teaching, weightlifting, and training for runs for at least 10-15 hours a week. My body fat percentage never went above 10-12% (measured with calipers 6 points).
Within 5 years after stopping teaching and letting life get the best of me, (career, marriage, instant family with step children, asthma getting bad) my weight and all of the other indicators start getting out of control - high blood pressure, high cholesterol, etc.
Because of asthma and a few other things, I couldn't work out how I use to my cardio vascular system won't let me and I needed to eat better - not just less - to get healthy again.
I gave up on the heavy cardio stuff I use to do and started back working out by focusing more on exercise that required muscular endurance - lifting weights, walking briskly at a high incline, and the elliptical at a high incline and steep resistance.
I noticed a big difference. My weight started coming down, I actually enjoy exercising and it takes a lot more discipline for me to take a day off from exercising than keeping to my schedule.
On the food side, since I'm acutely aware of how much exercise I have to do burn calories, it doesn't take much discipline not to eat too much and not wanting to die from self inflicted causes (eating crap) it helps me stay motivated to eat correctly.
On the other hand, if I live my whole life completely giving up pleasures that are "bad for me", it's not only a mental drain but what type of life is that? It's just like spending all of my time working and not being able to enjoy the money I earn.