Not everyone can be a vegetarian without damaging their health. Spiritually and emotionally, I sympathize with those who want to be vegetarian very much. But I am impatient with vegetarians who think that everyone can or should be vegetarian. It definitely would not work for me, since I am allergic to soy (a very common allergy) and quinoa. Since we, like other primates, are clearly omnivores, not herbivores, I don't recommend a vegetarian diet for anyone who is not willing to put in the time to be sure that they are eating a diet that is healthy for them. Simply dropping the meat from your diet without looking at the healthiness of that diet will very likely be bad for your health.
Having said that, it is very clear to me that in the US we eat way too much red meat, and cutting back on it (depending on what you substitute for it) would benefit many people's health and also greatly benefit the environment. (Personally, I don't eat red meat.)
In the book, Eat Right for Your Type, the author's theory is that only people whose blood type is type A are able to eat a vegetarian diet without damaging their health. I have no idea if that is correct or not and have not seen any research on it, but many people praise the book for helping them improve their health. A well known acupuncturist has pointed out in a book of his that in China only people who were Buddhist priests or monk made an effort to be vegetarians and his theory is that when you are meditating for hours a day, vegetarianism might work for your health but modern, hyper busy and hyper stressed people don't benefit from simply dropping meat from their diet.
In other words, these issues are complex, and I, personally, would like to see people who care about the planet experiencing great health and having lots of energy to do the things that they want to do. There are ways reduce the impact of your diet on the planet without going vegan.
BTW, because of the popularity of high protein quinoa with vegetarians, the indigenous people in the Peru area are unable to eat their traditional diet because the quinoa grown there is all for export. Yes, our diet, whatever it is, has an impact. No, it's not simple.