"Vegetarian athletes can meet their dietary needs from predominantly or exclusively plant-based sources when a variety of these foods are consumed daily and energy intake is adequate," Ghosh wrote in his presentation. Source
It requires eating a wide range of vegetables, fruits, grains, and legumes, but it's not hard to include all of these ingredients in daily meals. It's important to learn a few good recipes that combine nice flavor and an abundance of plant-based ingredients. If competitive athletes can operate at the extremes of human performance and be vegans, those of us who do not put great physical demands on our bodies should have no problems with the vegan lifestyle as well!