First point, the word of the Lord came to him. We are given no indication that Jeremiah was seeking the role as prophet.
Second and related point, Jeremiah was not an adult when the Lord sought him out.
God came to the unprepared, unconfident Jeremiah and assured him that he would be capable of doing the work to which he had been called, "I'll tell who needs my words, and I'll provide those words for you."
And, I'm wondering how seriously we who have been baptized take the call made to us.
For instance, who are these "nations" in verse 5? Who is included in this "all" in verse 7? The link the lectionary makes to Luke 4 is helpful (sometimes, another word for disturbing?).
First point, repeated: God does the work. Read verses 9-10. The Lord says, "I have given you the words. I have appointed you to speak to people you may not approve of or who have customs you don't understand, or don't look like you."
The message includes destruction and restoration.
To uproot and pull down. To destroy and overthrow.
But not just that, also to build and to plant.