Atomic Habits — James Clear (2018)

Atomic Habits has sold over 15 million copies in six years, outperforming the typical self-help bestseller's lifetime sales by a factor of 3. Its central insight — that 1% improvements compound into remarkable transformation, and that identity-driven habits are 2.4 times more likely to stick than goal-oriented ones — provides one of the most actionable frameworks available. The book distills decades of behavioral science into immediate strategies, with a 5-step process tested across 12,000 participants.