I have met many ministers who have no calling. They do what they do because they don't know what else to do. They do what they do because they genuinely like church and people. They do what they do because their mothers or fathers expected them to do this.
But they have no calling.
A calling from the Lord is an unqualified acceptance of His will. It is saying that you will go wherever He tells you to go and serve in any capacity He wants you to serve. It is saying that you will wait for His will before you will act. It is a daily devotion to Him.
A "called" minister is available all the time. The work can never become a job. It can never be a clock that keeps you at the church. No Bible study or sermon can just get by. The calling urges the called minister to give His Lord glory. He or she gives the very best. No amount of time can measure the best.
The called minister is always aware of his calling. He knows he is to reach souls. He knows he is to make disciples. It makes him dream of what he should be doing. It makes him pray and read the Scriptures diligently to hear a word from the Lord in the direction he should take.
The "calling" directs the called ministers life. His first concern is to His Lord. He knows that His Lord will provide for his family. He knows that His Lord doesn't want him to abandon his family. His Lord will direct his days so that there is time for the family. It may not be the amount of time each day that his family wants but it will be what they need.
My disappointment in ministers has come while we interviewed Music Ministers a couple of years ago. Their calling was qualified. They asked how many hours they were expected to work or told me that they were not going to serve a church very far from where they were raised. One told me that he was looking to make a step up to a "First Baptist" church and didn't think that he could do that after serving at our church.
Calling is not about salary, location, position or timing. Our only answer to God's calling is an unqualified "Yes!" Otherwise, all you are is just a hired hand.
Hebrews 11:8 (ESV)
8 By faith Abraham obeyed when he was called to go out to a place that he was to receive as an inheritance. And he went out, not knowing where he was going.