On the Incarnation by St. Athanasius. This is a short read (about 100 pgs) that I highly recommend, especially the edition with an introduction by C.S. Lewis.
In the book, Athanasius defends the need for God to come to earth as a human and builds a case against pagans who would laugh at this "absurd" notion. And who better to write on the topic than Athanasius, since he is best known for his relentless fight for the belief in the deity of Christ. In fact some say that he alone stood in the gap to protect Orthodoxy against ultimate corruption.
As a result, he faced much persecution. As Bishop, he was in and out of exile four more times, spending a total of 15 years away from his work in Alexandria. But even in exile, he was able to redeem the time, fellowshipping with monks, eventually writing a 'best-seller' about the life of Antony, one of the first monks. Many would see an exile as time wasted, but God used Athanasius' writings from this period to lead many to faith in Christ.
Nothing sweeter to the soul than to dwell on the person and work of Christ. Reading this book will help you dwell there.