He 'selflessly' volunteered to help.
a 'selfless' act
(..) The factions. Why do you have all of them? I don't want to be just one thing. I can't be. I want to be brave and I want to be selfless... Intelligent and honest and kind. Although I'm still working on "kind." I don't wanna go too fast. It's okay. I've already got my spot on the floor. (..)2014 Divergent