Exercise slowly and carefully. Start with modest amounts and then increase. You may need instruction and coaching. Gentle exercise should be a daily routine. Warm up before exercising.
Heat can help.
If your joints are stiff, take a warm bath or shower just before exercising. Or apply a heating pad or hot pack to stiff joints. Pick a time of day to exercise when you are least stiff and have less pain. If you take pain relievers, take them one hour before exercising. Avoid bouncing or high-impact exercise.