Background The American Heart Association recommends focusing on 7 health factors (Life's Simple 7) for primordial prevention of cardiovascular health. However, whether greater adherence to Life's Simple 7 in midlife improves prognosis after myocardial infarction ( MI ) in later life is unknown. Methods and Results In 1277 participants who developed MI during the ARIC (Atherosclerosis Risk in Communities) Study follow‐up, a 14‐point score of Life's Simple 7 was constructed according to the status (2 points for ideal, 1 point for intermediate, and 0 points for poor) of each of 7 factors (smoking, adiposity, physical activity, diet, total cholesterol, blood pressure, and fasting glucose) at baseline (1987–1989). Hazard ratios for composite and individual adverse outcomes of all‐cause mortality, cardiovascular mortality, recurrent MI , heart failure, and stroke were calculated according to Life's Simple 7 score. During a median follow‐up of 3.3 years, 918 participants (72%) had subsequent adverse outcomes after MI . Life's Simple 7 score at middle age was inversely associated with adverse outcomes after MI (adjusted hazard ratios of composite outcome, 0.57 [95% confidence interval, 0.39–0.84] if score is ≥10, 0.78 [95% confidence interval, 0.57–1.07] if score is 7–9, and 0.82 [95% confidence interval, 0.60–1.11] if score is 4–6 versus ≤3). The association was largely independent of access to care and MI severity. Individual factors related to better prognosis after MI were ideal nonsmoking, body mass index, blood pressure, and fasting glucose. Conclusions Optimal Life's Simple 7 at middle age was associated with better prognosis after MI in later life. Our findings suggest a secondary prevention benefit of having better cardiovascular health status in midlife.