Paul writes to Timothy again, but this time he is in a dungeon and about to be executed. He paints a very negative picture of the future, filled with persecution and people who fall away from the truth. In the midst of this, he urges Timothy to remain faithful.
We may not be sitting in dungeons waiting to be executed, but in every context there is some level of persecution and people who walk away from the truth. You may have been one of those people or had a close friend or family member do so. Paul urges us, as well as Timothy, to stay strong.