The place God calls you to is the place where your deep gladness and the world’s deep hunger meet. Frederick Buechner
Paul, the apostle, in his salutation to the churches in Galatia, states emphatically that he was called and sent by God to be an apostle. (The word apostle, by the way, means "sent," particularly on a mission.) There were many detractors who questioned Paul's authority and his calling, but it's evident that his mission and ministry made a huge difference for the kingdom of God.
If you google or do a Bing search for the words vocation and calling, you'll get sites galore, many of them posted by colleges, seminaries, and churches. Catholics seem to lead the way, especially with youtube videos about calling. Do a search and see for yourself. So it's a definite area of interest, especially to persons of faith.
I can remember the experience of being called to vocational ministry as a teenager. I can also remember trying to run away from the commitment I made, only to be led back gently by God upon my return from Vietnam. There was nothing dramatic about it, but God seemed to orchestrate circumstances to point me in that direction and to even provide funds via the GI Bill for me to complete college and seminary.
Now, before I go any further, let me state emphatically that there are many callings and many vocations in which God can use us. We aren't all called to be missionaries or ministers, but we are all called to make a difference for Christ's sake, even in vocations such as airline pilot, home builder, teacher, banker, or butcher.
The questions to ask are the ones that Buechner's quote above raises: Is this vocation personally satisfying and am I touching lives with the love of Jesus?