Reading the Legacy of Sovereign Joy has been very edifying. Short bios of Augustine, Luther and Calvin, with brief application.
Here are some quotes by and about Luther.
Page 87, Piper and Meuser: "Between 1510 and 1546 Luther preached approximately 3000 sermons.... Never a weekend off... never any respite at all from preaching, teaching, private study, production, writing, counseling."
93, Luther: "For a number of years I have now annually read through the Bible twice."
94, Piper: "The Bible is the pastor's vineyard, where he ought to work and toil."
95, Luther, on reading: "A student who does not want his labor wasted must so read and reread some good writer that the author is changed, as it were, into his flesh and blood. For a great variety of reading confuses and does not teach. It makes the student like a man who dwells everywhere and, therefore, nowhere in particular."
97, Luther, on the importance of knowing Hebrew and Greek:
"Languages are the scabbard that contains the sword of the Spirit; they are the [case] which contains the priceless jewels of antique thought; they are the vessel that holds the wine.... No sooner did men cease to cultivate the languages than Christendom declined, even until it fell under the undisputed dominioin of the pope. But no sooner was this torch relighted, than this papal owl fled with a shriek into congenial gloom."
101, Luther, on diligence in study:
"Some pastors and teachers are lazy and no good. They do not pray; they do not read; they do not search the Scripture.... you cannot read too much in Scripture; and what you read you cannot read too carefully, and what you read carefully you cannot understand too well, and what you understand well you cannot teach too well, and what you teach well you cannot live too well.... This evil, shameful time is not the season for being lazy, for sleeping and snoring."