I've tried veganism, but I couldn't keep it up. My wife and I both have jobs that require us occasionally to attend conferences and meetings in other cities. Vegetarians have it easy: almost any restaurant or hotel can provide pasta or an omelet*. But if you're vegan, the omelet is out, and the pasta probably is, too: you don't know if the dough contains eggs, and the chef probably doesn't either, since his role in feeding you was to pop a # 17 into the microwave. Salads are available, but some salad dressings contain egg or milk products, and in a restaurant you don't know where the dressing came from or what's in it. So when you travel, you're pretty much restricted to a diet of lettuce and whatever fruit you can score -- and probably Kaopectate, after a while...
*Even in Iowa they know what pasta is. They don't EAT it, of course, because it doesn't contain pork. But they've at least heard of it.