Perhaps you have never heard of "Calvin's Golden Booklet of the Christian Life." If not, you need to read it. It is actually an excerpt from his Institutes that has appeared in book form and taken on a life of its own.
The book essentially defines reformed piety and spirituality. It was written to counter the ascetism and mysticism taught in the Roman Catholic Church (i.e. Thomas a Kempis). In our day it ought to be read because it cuts through the fog of the various evangelical views on the doctrine of sanctification. The book is short - well less than 100 pages and is perfect supplement for one's devotions.
Dr. David C. Jones, retired professor of systematic theology at Covenant Theological Seminary, has written an informative piece about this work. He traces its history and how it has become a staple in many circles. You can read his article, here.