As to his divine nature, it is clear that Jesus is perfectly and infinitely content and that we can neither add to that nor take away from it. However, we see that in His human nature, this is not the case. Because of His sufferings on our behalf and His union with His children, Jesus is able to sympathize with us in our weaknesses and temptations.
This being the case, we meditate on how our situations and our actions here on earth can either add to His joy (when we obey) or in some sense even cause Him grief (when we fall into sin). We see how this should motivate us to die to sins and live to Christ.