You can add me to the list, as I have RA, OA, Sjogrens, Lupus, and due to the brain fog am probably forgetting something... Anyway, I sew when I am "up to it". I find the sewing part is really the easiest. My biggest challenge is cutting out pieces. I work awhile till I can't stand it anymore, then stop and rest awhile. Rest is very important for us. Try not to over do. Take pain meds if you need them. It's hard to do sometimes, but I found the pain meds helped alot with the fatigue too, which enabled me to do more of what I'd like to do. For now, I'm sewing as much as I can, while I can. Which is good advice.
Right now my knee is my biggest problem, but in a few days it may be something else as it moves around.
Unfortunately, there is no magic answer. Just do the best we can when we can...
Hugs to all of you..