I try to do small stretches or going for walks (best on treadmills or even ground) when pain levels are too high to do the usual things. The most important thing is just to move, don't feel pressured to push yourself past your limits :)

Starting a daily morning stretching routine really helps with getting your joints to get used to movements and relax them, it can be very difficult to get into routines especially if you have daily pains but just remember to stick to them and let your joints relax after with a soothing warm bath

My rheumatologist told me the best kind of exercise for arthritic people is swimming, it’s low impact and can help your joints a lot. If you have access to a Pool or lake I would consider doing that. Also saunas are really good for arthritis, just for relaxing, in my area those are common things but I know not many people have access to that.