Jesus, defending his disciples (Mark 2:18-22), explains that their identity and and measure of life has been changed through their relationship with himself. They are now "sons of the bridegroom." Jesus was their life. Jesus was their reason for living. Since Jesus' ascension, Jesus' disciples now live "in between the times," already experiencing a measure of the joys of fellowship with Jesus, but not yet experiencing the fullness of face to face relationship with Jesus. So "the sons of the bridegroom" today will both fast and feast (in fellowship); they will both mourn and rejoice; they will both confess their sins and celebrate God's grace. It is a paradoxical kind of live in which the brightness of the heavenly reality continually pierces the gloom of earthly tragedy. We do not live as though the are not both pains and problems. But we also do not live as though our lives are defined by our pains and problems. Also, we do not live fleeing and fearing those unpleasant patches, nor do we frantically search for those brief flashes of earthly joy that only serve as distractions. Jesus is our Rock and our Joy in all situations.
Jesus continues in this passage with two short parables: one about the garment that needs to shrink, and the other about wineskins that need to expand. Since neither will, or can, they need to be re-made, or re-placed. They need to be Jesus-sized. As "sons of the bridegroom," we are clothed with the new garment of Christ's righteousness, in which Christ is no mere patch, but our whole set of clothes. Concerning wineskins, with the Spirit of Christ inside of us, we are able to stretch as He sees fit as the body of Christ, in the service of Christ. Our lives are marked both by constriction and expansion. We do not expect that Christ will accommodate Himself to the shape of our lives, as if we were the designers of our own lives. Rather, we submit to His Lordship and ask that He would re-size us according to His pleasure.
As followers of Jesus, we live both under the hand of God, and we walk by the Spirit of God. And we cannot really walk in the Spirit if we do not submit to God's hand.