Do not be deceived: God cannot be mocked. A man reaps what he sows. The one who sows to please his sinful nature, from that nature will reap destruction; the one who sows to please the Spirit, from the Spirit will reap eternal life. Galatians 6:7-8
Daddy was a raised on a farm so, when we lived where it was possible to have a garden,  he would plant one. He told about an incident that happened to him and his brothers when they were young boys. It seems that they were given the task of planting a row of corn in the family garden. But, being boys, they were much more interested in going fishing in a nearby pond than they were in planting corn.
They started out planting the kernels as close together as they had been taught to do. But as time went by, they began to plant them further and further apart. When they got to the end of the row, they still had a lot of kernels left. Rather than go back and replant the row, they decided to just dig a hole behind the barn and throw the remainder of the kernels in the hole so they could get on down to the pond sooner.
Well, you know what happened. The corn began to come up with so much distance between each plant that Grandpa got suspicious about how it had been planted. The thing that really sealed their fate was the corn that came up behind the barn.
In this life, as Christians, Paul warns us that we should be careful about what we sow and how we sow. If what we do is done out of pride and selfishness, we will reap destruction; but if our actions are done to please God, we will reap eternal life.
As I have observed, those who plow evil and those who sow trouble reap it. At the breath of God they are destroyed; at the blast of his anger they perish. Job 4:8-9
It seems that sometimes what we sow does not yield a harvest; but we must remember that some of our harvest will not be reaped here in this life. But some of what we sow may go ahead of us to heaven or be realized here on earth after we are gone. My mother-in-law was the most saintly Christian that I ever knew. She had a child-like faith in Jesus that was unshakeable; she could always see the good in everyone and she believed that every thing that came into her life would somehow be a blessing. She truly demonstrated that in her life, God was in charge. I remember her saying that she prayed everyday for her family. Her constant prayer was that each of her seven children would come to know Jesus during their lifetime. After she was gone to be with the Lord, her prayer was answered, even though she was not here to see it come to pass.
Let us not become weary in doing good, for at the proper time we will reap a harvest if we do not give up. Galatians 6:9