John Piper writes that Augustine offers a corrective when Reformed theology becomes joyless:
And we need to rediscover Augustine’s peculiar slant—a very biblical slant—on grace as the free gift of sovereign joy in God that frees us from the bondage of sin. We need to rethink our Reformed doctrine of salvation so that every limb and every branch in the tree is coursing with the sap of Augustinian delight. We need to make plain that total depravity is not just badness, but blindness to beauty and deadness to joy; and unconditional election means that the completeness of our joy in Jesus was planned for us before we ever existed; and that limited atonement is the assurance that indestructible joy in God is infallibly secured for us by the blood of the covenant; and irresistible grace is the commitment and power of God’s love to make sure we don’t hold on to suicidal pleasures, and to set us free by the sovereign power of superior delights; and that the perseverance of the saints is the almighty work of God to keep us, through all affliction and suffering, for an inheritance of pleasures at God’s right hand forever.
Source: The Legacy of Sovereign Joy: God’s Triumphant Grace in the Lives of Augustine, Luther, and Calvin, p. 73. You can download the book for free in PDF format.