Excellent site for keeping MSers active with wheelchairs or without. Very positive website with wealth of information. Activemsers site. https://www.activemsers.org/ms-exercise-guide

Are you a full time wheelie or are you ambulatory/part time? There will be lots of upper body workouts you can do. I use dumbbells at home and follow caroline girvans workouts but adapt them to suit. I'm an ambulatory user though so can also do some lower body stuff as well. I often give myself daft challenges in the chair e.g. to climb the steepest local road hill.