I think the real reward lies in the joy on someone's face. Or rather relieve. And a rather familiar feeling if you had once been in a similar situation. I think the world needs more kindness. And in my opinion true kindness does not come with any expectations of gain in any way. When you help someone, do so because you want to. Not because you want to remind them ever so often, or use it as publicity.
In fact I think acts of kindness should be done completely anonymous. But kindness is often mistaken for weakness. Be very careful where you show kindness. We live in a world where kindness is also often exploited as opportunity.
What do you think Penny Hoarders? Has your kindness ever been exploited?