Every once in a while, a prejudiced meat-monger will say something like, “Yeah, of course so-and-so looks poor and sickly. He’s vegetarian.” This is, of course, nonsense. Some vegetarians may look thin and unhealthy, but not because they are vegetarian. It is usually a result of inadequate nutrition (which is not an inherent problem of a vegetarian diet), lack of exercise, other health problems, or just the dour personality of some.
A post “Almost Vegetarian: Famous vegetarian athletes” contains a list of athletes who have been vegetarian. Quite fascinating, and it certainly disproves the notion that you can’t be a strong, active, well-built person when you have a vegetarian diet. (The comments section of the post contains more names and references.)