We should set a good example for one another, especially with those who live nearby, in the neighborhood or in our home. We need to help each other and, in every way, stir one another up to do good. So in this verse we see the benefit of encouraging one another. When we turn over to Hebrews, the third chapter, we see deeper into the importance of encouragement, as the writer to the Hebrews calls it good prevention against the heart-hardening effects of sin. In the short time we have together we need to spend all that time doing good to one another.
Yesterday is gone forever.
Tomorrow will never get here. Hard hearts don't harden over night. They harden after first one and then another day slip by with no encouragement. Pretty soon the days pile up with our brother or sister sinking down further and further. Before you know it, heor she has given up, gone bitter, dried up spiritually, resolved to stay home, pull down the shades, and quit answering the phone.