I've had this book for a long time and recently re-read it. While it's targeted at System Administrators (which I used to be in a previous life) a lot of it pertains to application developers as well.
He basically breaks it down into a series of steps:
I'd say I've gotten better at a lot of these since the first time I read the book. I've been managing my calendar and email much better. I've begun using tools like Ant and AutoHotKey to automate all those pesky chores. Still struggling with To Dos and priorities but after re-reading the book I've got some ideas on how to improve in those areas as well (carrying my ancient Palm Pilot around again!).
Overall a great read. Check your local library for a copy. O'Reilly also offer it in PDF format as well as the hard copy.