Some people sacrifice themselves for others and practice goodness, but there are some who expect some price to be paid in return for their sacrifice. If they sacrifice with the heart of love, they might not want any rewards. Jesus took care of souls with true love and even gave His life, but didn't want any rewards. If you do good with true love you can enjoy true happiness just in doing good itself.
"But now faith, hope, love, abide these three; but the greatest of these is love" (1 Corinthians 13:13).