Why would God ask you to invest yourself in something or someone that didn't have a huge ROI??
Take for example, why would God ask you to mentor when the results lack despite your efforts poured into a person's life?
The answer is found in one simple word: obedience.
One thing I am learning is that what I do or do not do is not based whatsoever on outcome but upon obedience to God's call.
We've got to hear His voice in our ear and follow it unquestionably even when the outcome is less than stellar.