I occassionally volunteer in my spare time by giving blood, improving trout streams, or help at food banks. Do you do any volunteer work?
Not at the moment. I would love to donate blood, but not sure if I can. 
Well, volunteering is an altruistic activity so it comes in many forms. You could try something else if it might be easier!
This is true. So, what is involved in improving trout streams?
It varies, but generally you put barriers on the sides, add netting to rocky areas, and deepen the habitats so wildlife can live there. Volunteer work has many positive benefits including..well..happiness xD