I have tried to instill in my children that a hero doesn't necessarily save hundreds of people, they may just make the life of one person a better place. Even volunteers are heroes, whether young or old, because they make the world a better place.
This year, it was my quest to find "young heroes" stories to share with my children. I also do volunteer work with children and shared these stories with them too. I purchased this book and my children and I read it together. Wonderful, heartwarming (and heart wrenching!) stories" (yes, it has a goofy title!)
Also John Tesh had a great list of volunteer associations that were founded by children. I can't seem to find that list but this list is close:
These are awesome life lessons that you are teaching your child. Getting him involved in giving to Salvation Army or related charities, regularly, is a great start. Sometimes, at this age, seeing people at a soup kitchen is a little scary, so donating at this point is great. Teaching him to become a volunteer just has to be at his maturity and comfort level. Seeing you volunteer and giving money to Church or charities instills those qualities in him, too. Very powerful.
Every year, around Christmas, I would bring my children to a local nursing home and we would pass out simple gifts. One year, with the nursing home's permission and guidance, we handed out drinking glasses w/ hard candy. Another year, we gave away 8"x 8" little cloth pouches that they could carry stuff in - hanging it over the arm of a wheel chair. I had to warn my kids that, not everyone will be pleasant or will want us to approach them. However, sometimes people will want to hold your hand and touch you and, yes, my children put up with a lot of hugs and cheek pinches - especially my son who is the younger one.
Cub scouts, 4-H and organizations like that, give children opportunities to volunteer, too. Animal shelters are also a great place to go, if it doesn't sadden him, at this age, to see the animals in cages.
What a great mom you are to raise a son to have humility and compassion. I haven't forgotten to give back either - learned it from my mom!