I am 42 and still roll regularly, I do Judo, BJJ and some MMA now and then. It's still great fun, although, yeah it's hard.
Mostly I think I have a little harder time than many cause I have severe spinal arthritis, and pretty bad arthritis in all my other joints, my right collar bone is eroded at the shoulder joint from arthritis and causes a lot of pain.
I have broken my back (cracked l3 l4 vertebrae) and torn ligaments, broken numerous toes, horribly broken finger, dislocated thumb, many deep tissue and bone bruises on calf (from Sasae gone wrong), and well, lots of other injuries. Last night some young spaz did a knee drop on my foot (well, my own fault for half assed throw), right on my 8 month old surgery spot, and today the foot is purple and well, it hurts A LOT. But when I stop rolling, it all hurts way worse, and lo and behold, I get injured just doing sitting on the couch anyway, so what the hell. I expect to be doing this for many years to come.
Also, on a side note, my main instructor is a 57 year old woman BJJ brown belt, and Judo Black belt, she's like maybe 110 pounds and regularly schools these young athletic guys who come in. Her husband, my other main instructor, is like 53, BJJ purple, judo black belt, decorated boxer, and police sgt. Both are still rolling strong and hard and doing fantastic.
I see no reason you can't do either judo or jits to a late age. You just keep rolling - even when you feel shitty, just keep rolling. Afterwards, you always feel better.
