I think I read somewhere once How volunteering can help boost your immune system. I don’t know if this is true but the idea seems to make sense to me. Could volunteering in the community and doing charitable deeds be a way to boost the immune system and speed up recovery?
If it makes you feel good, and especially if it removes any depression, yes.
Low-moderate intense exercise as determined by how the individual feels (not the description given to the actual sprint session), for short to moderate duration eg. jogging, low intense tempo, also improves the immune response.
Do a paid job that is good for the environment…you get both the feelings of altruism and the ben franks.