Kempis puts the words above on Christ’s lips (3,3). In this rather lengthy monologue, the Lord bemoans the fact that so many listen to the world and the flesh, even in small matters, than they listen to Him. It will not turn out for these unfaithful ones.
Jesus’ lengthy Last Supper Discourse continues with the famous analogy of the vine and the branches (Jn 15:1-8). Remain attached to Jesus (the vine), feeding from Him (as branches do), accepting the pruning of the Father (the vine grower), and one bears much fruit. Those who do not desire the life giving nourishment of the Lord wither, die, and are tossed into the fire.
How do we bear fruit? By having “[Christ’s] words remain in [us].” In these posts, I never tire of tying belief in Jesus with living an authentically Christian life. Those who claim that belief and salvation only entail a verbal acknowledgement of Jesus as Lord and Savior, without concern for behavior, scandalize Christians and non-Christians alike. We are called to interiorize the Gospel then exteriorize it in word and deed. Jesus today, and repeatedly in the Gospels, speaks of the necessity of good works to attain heavenly glory (never forgetting the gift of grace necessary to do such deeds). Meanwhile, this disposition also allows us to bear much fruit here: the Lord closes this passage by saying that doing so is the mark of a disciple. Will their be pain involved? Guaranteed. It hurts to be pruned of our worldly affections and disordered inclinations. But the gain is eternal life for us and for those whom Christ brings along by working through us.