I am only 42 but have significant knee problems which do have an effect on my training, some days much greater than others.
You know that expression the heart is willing but the flesh is weak? Well that's often how I feel. I want so badly to do so much with aikido that jsut will never be possible for me.
It was really hard for me to face the fact that there are some things I will never really get to fully experience in my aikido training since I came to it later in life. No shikko, swari waza and very very little hanmi handachi will feature on my tests as I advance through shodan and beyond. My teachers have had to modify my tests for 3rd and now 2nd kyu in order to accommodate the fact that I can't do any of those things. I really struggled with the fact that this was necessary if I were going to train long term rather than try to force myself to do them and take the risk of injury that would be almost certain.
Some nights I have a lot of pain while I am on the mat. But I find that the training helps me to stay more flexible and things would only be a lot worse for me if I quit moving. Often I run up against things I just can't do the way sensei wants me to because of my joint issues but we just find another way to make it work. I suppose that this is the part where you find out how to do your aikido instead of just becoming a carbon copy of someone else.
Last week we had Mary Heiny sensei in the dojo teaching. This woman is an inspiration at her age with a hip replacement and a knee replacement and still she continues to not only teach but to improve and develop her own aikido. She is still learning as well and she isn't letting her age and physical problems hold her back so I won't either.