You are a lover
You are a Human being and you do things at cost to yourself and the to the benefit of others. Why would you do such things?
Love.
If you are a Christian, you have pledged fealty to a God of love. A God who will carry into his eternity the cost of sacrifice beyond human comprehension so that you may carry into your eternity unimaginable joy.
Go forth lover you – do your thing.
“And our charity must be a real and costly love, with deep feeling for the sins in spite of which we love the sinner – no mere tolerance, or indulgence which parodies love as flippancy parodies merriment. Next to the Blessed Sacrament itself, your neighbor is the holiest object presented to your senses.”
C.S. Lewis from “The Weight of Glory”