Master the art of caring without being controlling. Remind yourself or the other person to have boundaries and to listen to my body, or else there will be consequences of pain and discomfort but without forcing them to stop what they are doing.
You can offer a snack and say, "Oh, maybe we should sit down for a moment." Understand that in many moments we are enjoying all the things our bodies allow us to do. So let them enjoy those moments, even if you know they will probably have a flare-up later. Don't say, "I told you so, you're trying too hard," or "You should have done this," or "You should have done that." Just remind them, give ways to help, look for possible solutions, and understand my autonomy.