Pastors shouldn't enjoy it, but the heavy burden they bear is to sometimes fight. Paul starts this letter by reminding timid Timothy to challenge false teachers and their teachings lovingly but firmly, and he's now returning to that thought. It may be a heavy weight for the pastor to bear, but Timothy, unlike these false teachers, was no usurper and mustn't lack confidence in what is true and right. He must stand strong, fighting the good fight. These are qualities that, to some degree, all Christians should strive for, but they should also pray for and encourage their pastors to take up this call.