I have never been a natural runner. My best hope of winning medals when I race is finding a very poorly attended, short race. I don’t mean to suggest I’m terribly slow, though. Within the past 10 years I’ve run a 5K at a 6:15 min/mile pace and a marathon (26.2 miles) at just over an 8:00 min/mile pace. For a non-competitive runner I was super thrilled with those results and I worked awfully hard to get them.

My first marathon was 2002, in Toronto. That also happened to be around a year after I had given up dairy and transitioned from a vegetarian diet to a whole-foods, plant-based diet. I had been working on The China Study with my Dad. I think I was able to run better than I ever had my entire life, despite growing up playing soccer year round through to the end of high school. After getting hooked on the excitement of a group of people together running 26.2 miles straight, I haven’t quite kicked the habit. I have now completed seven plant-powered marathons.

So trust me when I say that I believe that exercise is important for health. It’s important for your heart and blood vessels, your lungs, your muscles and bones, and your brain. Exercise plays an important role in cancer risk, cardiovascular disease risk, osteoporosis risk, mood, weight control, and risk of dementia. I would never suggest that exercise doesn’t matter and, personally, I spend a lot of time incorporating exercise into my life.

And yet, when I discuss lifestyle with my patients I spend almost all my time talking about food. My new book, The Campbell Plan, contains just about a page on exercise. Am I delinquent? Perhaps I am. We know how crucial exercise is, but what I see more often than not is an overemphasis on exercise. I tend to see people focus their energies on getting to the gym as their primary strategy for weight control while leaving their diet largely the same. Perhaps they are trying to eat less, or just not snack on the junk in the house as often. Overall, this is a poor strategy.

Exercise needs to be part of your lifestyle but you need to build your health from a base of good nutrition. You cannot outrun a bad diet. The good news is, as my personal story might attest, once you get a good base of nutrition, you will want to exercise. A plant-based diet provides an excellent base for health and physical activity.