Hmmm, if you really want to do some aikido specific fun training when you're not supposed to, I guess you could be more conscious of your center when you do regular household chores, or when walking in a crowd, just being aware of your space and how your space relates to other people's space while on the move. or just breathing in time with your current activity.
That way, it is not too physically taxing but the awareness really helps.
Just my 2 cents.
Get well soon.