The Prize of the High Calling   by Charles H. Welch. 
This book is an exposition of the epistle to the Philippians, and derives its title from chapter 3:14, "I press toward the mark for the prize of the high calling of God in Christ Jesus."  The purpose of this book is to exhort believers to service by examples of our Lord first, then Paul, Timothy, and Epaphroditus.  The Lord's desire for each of us is that we grow from newborn Christians to full grown adults.  We can accomplish this by keeping our eyes on the end that God has in view.