I'm trying to think of an example of a volunteer opportunity that our family takes part in that my kids don't at least see the value of doing, even if they don't particularly enjoy it.
It's a kind of chicken & egg thing to me. Which came first? Was it my children's understanding of how they can be useful to others in the world (and their understanding of how good it feels to help others) or was it their desire to help wherever they can?
I think that, even when bored because it's 'my cause' and not one that they understand yet, they are still learning through my role modeling that you need to get in there & get your hands dirty if you hope to create change in the world.