That's the catch 22 with BJJ, it's both great and detrimental for your physical health. Joints in particular you have to watch out for. Both of my knees are in rough shape as well as my left shoulder and as luck would have it we were working on arm bars earlier this week. I tap super early on those because I don't have great range of motion. I know when I can defend and fight and when it's time to tap. Take downs are really difficult for me because I can't move explosively, my body just can't do it, those classes are always really defeating to me because I'm at a disadvantage. I try to be smart about who I partner up with, there's a couple of guys my age, size, and experience level and we're all respectful of each other's abilities and limitations. The main guys I try to stay away from are guys who are really young because they try to overcompensate for lack of experience with going too hard. I also steer clear of guys who are way too big, I can roll with some but any white belt who outweighs me by more than 50 pounds is risky, the higher belts that big are more trustworthy to be safe. I legit don't care if I win or lose to anyone, I just don't want to be injured and I have no problem sharing that with my partners. At my age those are the guys who end up leaving and not coming back, the guys that get hurt. I've seen plenty of guys in my 18 months have something happen and just stop coming.
After about 6 months of training it feels like everyone's pride has been leveled off enough that losing all the time isn't as bothersome. It's odd at first that it's easier to accept losing once you understand more about it. I never had any misgivings that I would pick BJJ up quickly, but the losing and not understanding can take a toll on you mentally.
I hope you heal up and can get back on the mats soon. Once you make it part of your weekly routine it's tough to go back.