Not saying you would have been a Olympic medalist, if you would have eaten meat. But sorry, you realize high quality animal nutrition is vital to human athleticism and health. Does he realize running is catabolic(hint that means you need to rebuild what you broken down)? One of the best examples of the importance of animal nutrition in the human diet, is the work done by Weston A. Price. Look into him if you want more info. Also, many of the top protein experts in the world say we need a lot more protein.
https://www.youtube.com/watch?v=PlIE_v3w7UIhttps://academic.oup.com/ajcn/article/101/6/1330S/4564493Also look into many of the plant toxins.
https://www.youtube.com/watch?v=TS60m_dawcMhttps://www.youtube.com/watch?v=fnjX3cZ4q84This idea you should base your diet around plants, or only eat plants is foolish.