Aristotle's Ethics by Aristotle

Tenacity is the power of resisting the pain arising from desires for certain pleasures; softness is the inability to resist such pains. While pleasures are the sphere of continence and incontinence, the experience of pain does not enter into determining whether or not a man will commit an incontinent act.

Two forms of incontinence can be distinguished—impetuosity and weakness. Weak people deliberate before acting, but are not strong enough to adhere to the results of their deliberation if it conflicts with their desires or emotional mood. Impetuous people act emotionally in haste without bothering to deliberate.