Keep a song in your heart.
God rewards selfless acts done in secret. It's in the Bible, Matthew 6:1, TLB. "Take care! Don't do your good deeds publicly, to be admired, for then you will lose the reward from your Father in heaven."
God rewards us abundantly. It's in the Bible, Matthew 19:29, NIV. "And everyone who has left houses or brothers or sisters or father or mother or children or fields for My sake will receive a hundred times as much and will inherit eternal life."
God brings us our reward. It's in the Bible, Revelation 22:12, NIV. "Behold, I am coming soon! My reward is with Me, and I will give to everyone according to what he has done."