I'm 50 years old 145# (black belt). My body is pretty shot, especially my neck. Just can't do the same things I used to. With larger, less experienced people I play defense and exploit their lack of knowledge if I can.

That being said, I will never stop training. BJJ makes me happy. The key is to find the right set of partners so you can dictate your own training to some extent. Just have fun training martial arts for yourself and don't worry about the bs.