Eating. Eating a lot. And not worrying about it. Sure, it's possible to be an unhealthy vegan, comsume nothing but processed veggie burgers, fake cheese loaded with saturated and trans fats, waffles, chocolate, hob nobs, etc - but in reality, what you're eating is never going to be as fatty or as bad for you as a meat and dairy diet. It's almost impossible to consume cholesterol on a vegan diet, for example. Most of what I eat is fruit, vegetables, beans and rice or pasta.
Even vegan cake is relatively guilt free - it still has a lot of sugar and some oil or marg in, but no butter and no eggs makes for a far trimmer treat. And it's dead easy to replace sugar with date syrup, agave, pureed prunes or apple sauce if you're feeling particularly healthy.
Yay for eating lots. I like eating.