Congrats Carla and Dan, and thanks Carla for re-opening this thread on a "touchy" subject. I'm still vegetarian (of course) and nearly vegan (cheese is my only sin), and exercise on a regular basis (almost daily). There is a lot of evidence, beyond anecdotal examples, that shows how plant-based diets, in combination with exercise and some relaxation techniques can have drastic effects on one's health. I was disappointed to see Mark Head's earlier comments (I think he's a doctor himself, but Mark, how many nutrition classes did you take, and what year were those?).
Dr. Dean Ornish has conducted a bunch of studies in peer-reviewed journals like the American Journal of Cardiology which clearly show how diet and lifestyle changes can radically improve your health. Sure, smoking isn't good either. A no-brainer. Here are some of his studies
http://www.pmri.org/research.html#articles (sorry, not direct links, as most journals aren't open to the public, but you can get abstracts and a general feel).
I'll just keep on doing what I'm doing. There is no one silver bullet to good health, and happiness is certainly a component. But healthy eating can be a big part of a happy life. Better get to bed, big soccer game in the morning if the rain holds off....(my kiddo is bottom right, healthy vegetarian at 97%+ percentile for height and weight in the growth charts at age 4, and I'm the coach, rolling in around 175 lbs - good fighting weight)...Cheers!

Dr. Nimbus Couzin