Knox's Example in Not Entering the Ministry without a real Calling

Here we read of John Knox answering the call to the ministry as called out by John Rough.
If ever there was no man more suited to the ministry and who worked great things by the power of God by his ministry, it would be Knox. Yet today, it often seems, that people enter the ministry without any real calling to. They may have some notion that they can do good, yet, if unsuited and it not being their true calling, they may be responsible for being the instrument for many souls to perish. Being a Christian, is no reason to think one has what it takes to be a minister of the Gospel. The state of the ministry today, in much of Christendom, validates this. The call if the ministry is a very special and high calling. Those who have the calling and are faithful ministers for Christ and his gospel, is a different thing entirely from those who on some notion that has nothing of God given wisdom behind it, think themselves fit to enter the ministry to do so, and do far more harm than good, and far more work for Satan than for God.
No fitter candidate for the office of Minister existed than John Knox, yet he recognized the great responsibility that went with it, and he wrestled with it, heavy in heart, because he didn't want to go where he was not truly called to be. Oh for more men to take notice of Knox's example in this way, and for many to recognize, that unlike Knox, they do not have what it takes to be a minister of the Gospel, without doing Satan's work. Passing all one's exams is one thing, but head knowledge never did make a heart what it needs to be, for any mission or calling in life.
As told by Thomas McCrie in his life of John Knox, of Knox's anguish at this time in his life after John Rough called him out publicly to take up the call of Minister of the Gospel of Christ:

This scene cannot fail to interest such as are impressed with the weight of the ministerial function, and will awaken a train of feelings in the breasts of those who have been intrusted with the gospel. It revives the memory of
those early days of the Church, when persons did not rush forward to the altar, nor beg to “be put into one of the priests’ offices, to eat a piece of bread”; when men of piety and talents, deeply impressed with the awful responsibility of the office, and their own insufficiency, were, with great difficulty, induced to take on those orders, which they had long desired, and for which they had labored to qualify themselves. What a glaring contrast to this was exhibited in the conduct of the herd, which at this time filled the stalls of the popish Church! The behavior of Knox also reproves those who become preachers of their own accord; who, from vague and enthusiastic desires of doing good, or a fond conceit of their own gifts, trample upon good order, and thrust themselves into a sacred public employment, without any regular call.
We are not, however, to imagine that his distress of mind, and the reluctance which he discovered in complying with the call which he had now received, proceeded from consciousness of its invalidity, by the defect of certain external formalities which had been usual in the Church, or which, in ordinary cases, might be observed with propriety, in the installation of persons into sacred offices. These, as far as warranted by Scripture, or conducive to the preservation of decent order, he did not contemn: his judgment respecting them may be learned from the early practice of the Scottish Reformed Church, in the organization of which he had so active a share. In common with all the original Reformers he rejected the necessity of episcopal ordination, as totally unauthorized by the laws of Christ; nor did he regard the imposition of the hands of presbyters as a rite essential to the validity of orders, or of necessary observance in all circumstances of the Church.
The papists, indeed, did not fail to declaim on this topic, representing Knox, and other Reformed ministers, as destitute of all lawful vocation. In the same strain did many hierarchical writers of the English Church afterwards learn to talk, not scrupling, by their extravagant doctrine, of the absolute necessity of ordination by the hands of a bishop, who derived his powers by uninterrupted succession from the apostles, to invalidate and nullify the orders of all the Reformed Churches, except their own; a doctrine which has been revived in the present enlightened age, and unblushingly avowed and defended, with the great part of its absurd, illiberal, and horrid consequences. I will not say that Knox paid no respect whatever to his early ordination in the popish Church (although, if we credit the testimony of his adversaries, this was his opinion); but I have
little doubt that he looked upon the charge which he received at St. Andrews as principally constituting his call to the ministry.
His distress of mind on the present occasion proceeded from a higher source than the deficiency of some external formalities in his call. He had now very different thoughts as to the importance of the ministerial office, from what he had entertained when ceremoniously invested with orders. The care of immortal souls, of whom he must give an account to the Chief Bishop: the charge of declaring “the whole counsel of God, keeping nothing back”, however ungrateful to his hearers, and of “preaching in season and out of season”; the manner of life, afflictions, persecutions, imprisonment, exile, and violent death, to which the preachers of the Protestant doctrine were exposed; the hazard of his sinking under these hardships, and “making shipwreck of faith and a good conscience”; these, with similar considerations, rushed into his mind, and filled it with
agitation and grief. At length, satisfied that he had the call of God to engage in this work, he composed his mind to a reliance on Him who had engaged to make His “strength perfect in the weakness” of His servants, and resolved, with the apostle, “not to count his life dear, that he might finish with joy the ministry which he received of the Lord, to testify the gospel of the grace of God”. Often did he afterwards reflect with lively emotion upon this very interesting step of his life, and never, in the midst of his greatest sufferings, did he see reason to repent the choice which he had so deliberately made.