God eventually removes all the physical accomplishments of the self-exalted person. Anyone who glories in himself will receive his true reward in the form of condemnation, debasement, degradation, and humiliation. Glory is praise, honor, or distinction extended by common consent. If we glory in ourselves, it is because no one else is glorifying us for our perceived accomplishments—probably because we have done no real, glorious deeds in the first place.
Martin G. Collins
Overcoming (Part 9): Self-Exaltation
Jesus warns against this in the Sermon on the Mount when He tells us to do our spiritual devotions privately. We are to fast and pray privately. We should not let everyone know what and how much we are studying God's Word. We should not draw attention to our good deeds. However, the pride in a person leads him to ensure he is recognized and honored for what he does.
Notice that this verse does not say that the proud's work was not a good one. It may indeed have been a good work. But for him to make sure that he gets the glory for it has the same effect on him spiritually as eating too much honey has physically: It tastes awfully good going down, but it causes serious consequences later on. That is the lesson of the proverb: Seeking one's own glory will someday result in negative consequences.
John W. Ritenbaugh
Faith (Part 6)