As I was reading your post the one thing that has come to mind are jigsaw puzzles. Get them at various sizes with pictures you like or places you may want to go at some point when you get bette. Start off small and build up. You don’t have to sit down for to long to do them and can come as go as you please. But the picture also acts as a motivator to get you thinking of what is needed to get to where you want to be. I also like writing lists and checking them off. I must admit I make small dumb lists like morning check list and make them very detailed. The only other things I can think to suggest would be Journaling, meditation, yoga and or swimming. I know they don’t seem like rewards but if you think of it as a time to unload your burdens it can be a reward. Just need to shift perspective a bit. Hope this helps. If not I wish you the best on your journey.