1. Jeremiah is called of God to be a prophet.
Jeremiah 1:5 Before I formed thee in the belly
‘President Nelson’s selection to serve as God’s prophet was made long ago. The Lord’s words to Jeremiah also apply to President Nelson: “Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations.” Jeremiah 1:5 Only three years ago, Elder Nelson, at age 90, was fourth in seniority, with two of the three senior Apostles being younger in age than he was. The Lord, who controls life and death, selects His prophet. President Nelson, at age 93, is in amazing health. We hope he will be with us for another decade or two, but for now we are trying to persuade him to stay off the ski slopes.’ (Neil A Andersen, General Conference, April 2018)
See: Give us strength according to our faith in Christ

Jeremiah 1:6-10 I cannot speak: for I am a child
‘Jeremiah felt inadequate and unprepared for his calling (compare the responses of Enoch in Moses 6:31 and of Moses in Exodus 4:10). The Lord reassured, encouraged, and endowed him with authority and power to do His work and speak his words. In verses 7-8 the Lord is saying, essentially, ‘Whomever I call, I qualify,’ which we have heard modern prophets reiterate. Jeremiah didn’t need to fear mortal, temporary leaders, for the prophet would be given power ‘over the nations and over the kingdoms.’ The Lord’s act of touching Jeremiah’s mouth to sanctify him for the ministry was paralleled by an angel in Isaiah’s case (Isaiah 6:7). Verse 10 uses some key words which seem to be a major theme in Jeremiah’s writings (see also 18:7-9; 24:6; 29:5; 31:4-5, 28; 42:10)’ (Andrew C Skinner, D Kelly Ogden, Verse by Verse: The Old Testament)
2. Many people oppose Jeremiah and try to prevent him from fulfilling his mission.
Jeremiah 26:7-11 Most of the people opposed Jeremiah
“Not surprisingly, Jeremiah’s words arouse immediate antagonism, especially among the priests and prophets of Jerusalem. In the account of the arrest and trial it is they who attempt to have Jeremiah condemned to death, while the princes and many of the common people apparently take his side. The religious leaders would have suffered greatly if the temple had been destroyed as Jeremiah predicted. The prophets who are involved in the present account are doubtless cult (false) prophets attached to the Jerusalem temple.” (The Interpreter’s Bible, ed. by G. A. Buttrick et al [New York, Abingdon Press, 1952] 5:1006-1007)

Jeremiah 26:12-15 Jeremiah courageously delivered the message the Lord had commanded him to give
‘The answer of Jeremiah is simple and straightforward. Yahweh, he affirmed, had truly sent him, but the sole object of his prophesying had been to avert the evil by leading them to repentance. If they would amend their ways God would deliver them from the threatened doom. As for himself he was in their hands, but if they put him to death they would bring the guilt of shedding innocent blood upon themselves and upon the city. ‘ (Barnes’ Notes on the Bible)
Jeremiah 11:19-21 Jeremiah was opposed by his neighbours
‘The Lord revealed to Jeremiah that the people of Anathoth, his own hometown, were plotting to kill him. He had been ‘like a lamb or an ox that is brought to the slaughter’ (v 19). Jesus later faced the same treatment in his own hometown. (Matthew 13:54-58)’ (Andrew C Skinner, D Kelly Ogden, Verse by Verse: The Old Testament)
Jeremiah 37:12-15 Jeremiah is cast into prison
3. Jeremiah is strengthened in adversity by his love for the word of God.
Jeremiah 15:16 Thy word was unto me the joy and rejoicing of my heart
“I used to ‘read’ the scriptures 20 minutes each day according to a schedule of what to read and when to read it. Then I discovered the joy of ‘studying’ the scriptures-and of pondering the meaning and impact on my life. If I don’t understand a passage or specific meaning of a word, I take the time to search the scriptures and satisfy my yearning to know God’s will. Using new tools such as a database of the computerized scriptures and related books, a whole new world of study and learning has become available. Studying, pondering and intense prayer have greatly impacted my life for good as I put into practice the new knowledge as it is received. Line upon line, precept upon precept, we can each progress along the narrow path that leads to eternal life.-Larry Strong, Kaysville, Utah” (LDS Church News, 1997, 05/10/97)

Jeremiah 20:9 A burning fire shut up in my bones
‘When I came into the Church I had a wife, but in a very few months after I was baptized I lost her, and she left me two little girls. I gave away what I had, and I started to preach the Gospel. I was obliged to do it, for I felt as though my bones would consume within me if I did not, consequently I devoted my time to preaching. I traveled, toiled, labored and preached continually. My own brother Joseph, and myself, were together a good deal of the time, until we went to Kirtland, to see the Prophet, and the next year moved up. This is the way I commenced, and when I gathered with the Saints I was about as destitute as any man that ever gathered to the gathering place.’ (Brigham Young, Journal of Discourses, 16:69)