In his Preface to The Roots of Endurance, John Piper wrote:

   As I write this Preface I have just preached to my people several messages in which I pleaded with them to be “coronary Christians,” not “adrenal Christians.” Not that adrenaline is bad, I said; it gets me through lots of Sundays. But it lets you down on Mondays. The heart is another kind of friend. It just keeps on serving—very quietly, through good days and bad days, happy and sad, high and low, appreciated and unappreciated. It never says , “I don’t like your attitude, Piper , I’m taking the day off.” It just keeps humbly lub-dubbing along. It endures the way adrenaline doesn’t.
   Coronary Christians are like the heart in the causes they serve. Adrenal Christians are like adrenaline—as spurt of energy and then fatigue. What we need in the cause of social justice (for example, against racism and abortion), and the cause of world missions (to plant churches among the unreached peoples of the world), and the cause of personal holiness and evangelism (to lead people to Christ and love them no matter what) is not spurts of energy, but people who endure for the long haul. Marathoners, not sprinters.

—John Piper, The Roots of Endurance, 11-12