[ishi]

Perhaps you should try a different teacher. I know guys who started training in their 50s and 60s, so it's entirely possible if you pace yourself, and not exceed the current limits of your body. Little by little, these limits get stretched and your physical condition improves. Of course it's easier if you're fit and flexible to begin with, but that's not a requirement.

[magic_beans]

I do Crossfit, weightlifting and run occasionally; my weight is slightly below average. I wonder if maybe my joint issue is just something with my own body? That said — the class was an all-levels class with full tumbling. Maybe an intro class would be better...

[robaato]

Try a different class/teacher - there are a whole host of ways to approach/practice aikido, and taking care of health should always be paramount according to my line of teaching.

I am still not very flexible - but with lots of practice I am softer than most of the flexible people who join the dojo :)

Things like wrists/ankles/knees need time to (many months) to adapt/get conditioned.

[rusk]

Do you do Yoga or Pilates? Or anything to help you with flexibility?