I have a trampoline - I have been meaning to get one of the smaller ones for use inside, for cold wet days.
The one in the garden means that I can use it easily and if I want to stop I can have a sit down and restart, or give up on it entirely for the moment and be back inside in half a minute. It is very low impact, makes a great surface for stretching or yoga and I think that my joints have actually improved since I have had it.
The small ones - 'trampettes' I have heard them called, are easy to move around and store out of the way so perhaps consider one of those if a more convenient and less avoidable type of exercise is required.