It is very difficult to find anyone today speaking of a theology of rest. Often we will find book after book devoted to being less busy or finding time to step away from constant work.
The problem is so ingrained that we often cannot put the solution in a positive light, i.e. rest or relaxation. We are often so far off that we can only think in terms of being less busy or making time.
The bible devotes an entire day in the life of a Christian for rest. Living out Sabbath means trusting that in six days we can do more with God than in seven days without God.
Among the few people today who keep Sabbath, it often becomes a very burden-full thing. It seems to equate in some circles to not enjoying oneself as if Sabbath is a rigorous denial of self.
Sabbath is made for man and not man for Sabbath. The concept of Sabbath needs always to have human joy at the center of it. Joy in God is of course the main part of man's joy, but God made all creation good.
It is often you will find preachers in the current day preaching to a person or two on a Superbowl Sunday. No matter how insensible opening the church is or how sensible moving the service a few hours earlier, they view it is a spiritual discipline to not buckle to culture.
In a sense the motive makes sense but the glorification of self denial is all to prevalent in the current day. Self denial in and of it self has no value. What has the self denial of the pastor produced? Often it seems to be something of a pride that they succeeded while 98% of the church failed.
You see too often self denial is pursued even when it produces no fruit. Sometimes self denial hurts rather than helps. Christianity is about joy and how joy may be truly found.
Rest is an important part of God's plan. God has come to draw people to himself and teach us how to be truly happy. He wishes for us to enjoy the world without being worldly.
Jesus often withdrew into the wilderness to pray and rest. If Jesus saw the need to rest (and he did) than we should try to see the need as well.