Where do you get enough protein to maintain muscle integrity ?
There’s plenty of vegan athletes and weight lifters. If they don’t have issues as an elite athlete I doubt the average person will have an issue.
It takes some effort, but it's fairly straightforward if you can find ways to substitute it into your daily meals. I like taking an existing meal and just replacing the animal products from it. One example I like is a chicken curry wrap. It's just chicken mixed with mayo, curry powder, celery and onions, all stuffed into a wrap. I've substituted a lightly fried tofu in place of the chicken and a vegan mayo instead.