willpower

"Willpower is a muscle. Every 'no' makes it stronger."

"Willpower muscles grow with daily reps."

"Willpower muscles grow with daily exercise."

"Willpower is a muscle that strengthens with use."

"Control your choices, shape your destiny."

"Control your choices, command your life."

"Control your impulses; command your future."

"Control your habits, own your life."

"Self-control is strength. Calmness is mastery."