I tried volunteering a few times, doing manual labor like cleaning up a pantry, organizing books for distribution, etc. it didn't work for me though. It felt like time truly was wasted for some reason, that's just my opinion though. Giving blood out at blood drives seemed like a much more worthwhile effort though.
I honestly don't recommend anyone doing manual labor for free if anyone is planning on volunteering. The fact that you are working for free and quite literally busting your ass for 2-3 hours at a time is not covered by that feel good feeling.