Many years ago E.Y. Mullins, a Christian author, wrote a tract entitled What Constitutes A Call to the Ministry. There are not a large variety of options for those out there discerning their calls to ministry. Today Lifeway provides a booklet on the call to ministry, and there is a new book called The Call by Ed Etheridge. So it's worth looking into other options: Mullin's work is brief, but here is a short outline of his opinion for our consideration. It may help to remember that this is the same Mullins who was president of Southern Seminary, a large US seminary, (SBTS) in the past.
The elements which enter into a divine call may be stated as follows:
1.) An abiding conviction of duty or desire to enter the ministry and serve God in this way. I say it should be a conviction or desire. By conviction I mean a sense of duty.... I have used the qualifying word abiding because the sense of duty should be permanent. They cannot escape....In some cases it is not so much a sense of duty as a desire. This also is permanent.
2.) Of course, personal fitness in body and mind and spirit is necessary. A man must be a regenerate man, he must have a reasonable degree of health, and he must have aptness to teach or capacity for aquiring aptness ot teach, or else he will not be a success in ministry. Usually God shows a man these latter qualities by using him in Christian work, in the Sunday School or young people's organizations, or otherwise. Then, too, the opinions of the brethren usually coincide and agree in the opinion that God is calling the young man into the ministry. Thus there is an inward call and an outward one. The two harmonize. The above elements which enter into it contain only the essentials. There are many variations in the experiences of men who are called into the ministry. God has manifold ways of making his will clear. No two men have exactly the same experience. Where there is perplexity or doubt, earnest prayer, consultation with friends and reading the Scriptures will usually in time develop into clearness the divine call, or show that it is not a call to the ministry.
Thinking critically about this, how might it apply to you if you're exploring this topic?
Would you add/change anything?
This is from the only copy (read: rare archives) I know of stating President Mullin's view on this in a tract. It may be of interest to you to know that the mentioned Lifeway materials on the subject today are remarkably similar in conclusions and main points. However they tend to be larger booklets rather than tracts, complete with places to interact with questions on one's call to full-time ministry. Maybe if you're searching the web on this topic, this can help a bit.