The Fruitfulness of my Fruitless Ministry

You did not choose me, but I chose you and appointed you that you should go and bear fruit. John 15:16
Some years ago I was troubled by how little fruit I bore. By this, I refer to the fruit of my Christian ministry rather than my personal life, though God knows I could be talking about either. Week in, week out, I would enter the pulpit and preach. Yet there were no conversions and little evidence of further growth among the believers. People seemed to enjoy what they heard and I could lead a meeting well enough. But where was the fruit?
Having sought the Lord about the matter, I asked Him to see some fruit or put an end to my preaching. As a result, I became aware of a couple of things. One was a young man who gave his testimony at a church in Lancaster. He told those gathered that he had finally responded to the gospel when a man called A. Marsden came and preached at his church. This was news to me; there was certainly no altar call or deep conversation at the church door. 
The second incident occurred a while later. The pastor of a church told me how I'd been to that church and preached, and through that God had called him to the pastorate. I can't remember that sermon, nor what was said. 
I have since learned that our labours for the Lord produce fruit we cannot always see. Charles Wesley could never have imagined the countless unborn millions who would be blessed by his hymns. So none of us know the extent to which God will use our acts of service. Although I preach at a little country chapel in the corner of a field, who knows what the Lord will do with it? In which ever part of the vineyard you labour, be assured that the Master will use your endeavours for His glory, with or without your knowledge. 
Why, though, does the Lord not fully apprise us of the fruitfulness of our work?
  • That we should not become conceited, thinking that God needs us and our skills. 
  • That we should not forget our status of beloved servants.
  • That we might better enjoy our time in heaven, meeting and greeting those whom we blessed without knowing it on earth.