Have you ever committed one of these?
I suppose that I did recently.
What I did was insignificant in the "grand scheme of things", but to the person who was on the receiving end...it will have positive effects.
So, I was happy to do what I did, and would do it again, without a thought, if I knew it would make just one random person happy.
If you ever do....it's the knowledge that you have helped make someone's day brighter that you get from it.
Just doing something random, can make another person's life lighter for a short while, and if it costs you nothing ....why not?