Called to the Ministry

I have been thinking a lot of recent times about what constitutes a call to the ministry. I have heard many speak on the subject over the years and read bits and pieces. There seems to be a great deal of emphasis on a subjective inner call, feeling, compulsion, and an awaiting for "the call." I have to be honest, at present I find this hard to square with the message of the Bible. Any Scriptural references quoted are for the prophets and all know that they had a unique roll and place in redemptive history.
From Ephesians 4 it appears that the pastor teacher is equipped to equip the people of God. Surely that equipping of God is therefore a huge part of a call to the ministry. The Lord Jesus Christ equips certain men so that they will be able to equip the people of God through the Word. My understanding is that a call to the ministry of the gospel constitutes three main areas: equipping for the job, calling of the church and inward desire. Where these are present surely a man can say that he has been called to the ministry. So what are the gifts for gospel ministry? Many launch straight for - preaching and teaching. Obviously they are central but on their own they are not sufficient. Does a man have wisdom. Has he been equipped to handle the complexities of the life of the church. Too often men have begun in the ministry only to come unstuck in a short period of time or cause great havoc simply because they lacked wisdom. This is where the roll of the church is so vital. The elders of a church ought to be able to discern not only can a man preach - but is he wise. Does he know what the Word says and know how that Word is to be worked out in life.
Another thing on ministry. There seems to a growing influence to wait until a man is older, has experience of life. Granted there may be situations where this is wise, it was so in my own case. But the other side of the matter is - a young man gifted for ministry and growing in grace as he trusts in the Lords strength can have a whole lifetime of ministry if he enters college as soon after university as possible. Of course such advice has huge implications for young men, men in their late teens - be redeeming the time now, grow now, read now, learn to pray now so that you will be ready to go into the ministry at the first possible opportunity.
Just some rambling thoughts. I trust that they might do a little stirring.