Here is a quote I'll be sharing this Sunday from John Calvin's sermons on Titus, on why and how we all (not just pastors) must always keep working at strengthening and revitalizing the local church:

Those whom God has called to preach his word he has appointed as masons in the building of his temple. It is the whole church that we build in common, and each of us must work at it, for we must take things forward as much as we can. But those who are happy with the present state of affairs are much deceived: it is a sign that they have not yet understood the goal to which God calls them, nor have they examined themselves, for we are very far from the mark at which we should be aiming. So let us strive as hard as we can to reach it, and let us carefully reflect on what we lack. Even when God graciously allows his word to be purely preached to us, and even when some tolerable order prevails among us, let us remind ourselves that all is not perfect and that the work is never truly done. This should not dampen our spirits but should rather prod and prompt us to observe Paul’s injunctions and to follow his advice (pp. 53–54).

If you are interested in learning more about the French reformer (whose thought profoundly shaped Presbyterianism, given that the Scottish reformer John Knox studied with him in Geneva), I'd encourage you to check out the following books: 

Biography: John Calvin, by Bruce Gordon
Theology: John Calvin on the Christian Life, by Michael Horton
Children: John Calvin, by Simonetta Carr