Simple exercise to boost will power

According to Kelly McGonigal in The Willpower Instinct, (p 40) 4-6 breaths per minute, or 10-15 seconds per breath for 1-2 minutes will increase your heart rate variability, which is a great predictor of whether alcoholics will relapse.

EDIT: For anyone interested she cites the work of Suzanne Segerstrom, a psychologist at University of Kentucky. Apparently they have identified something like the opposite of the fight-or-flight response called the pause-and-plan response..