I don't think it's the actual "things" he is talking about. I think it's the general intent and attitude behind the act of kindness.
Your legacy will be one of pleasant generosity and kindness. Placing others before yourself. If I should happen to outlive you, I think I will remember you like that. We've never met, but for all the years we've "known" each other, I can't remember a single time you were anything but good-hearted and amiable. (And sometimes a little wacky. )
“The things you do for yourself are gone when you are gone, but the things you do for others remain as your legacy.”