Drinking one or two servings of milk or yogurt daily

Cost: Only a few yuan per day, with no extra time required.
In plain terms: People who consume two or more servings of milk or yogurt each day have a roughly 17% lower chance of dying during the same period compared to those who do not drink any.
Benefit: The PURE study followed over 136,000 participants across 21 countries for an average of 9.1 years; 6,796 of them passed away. Those who ate two or more servings of dairy products daily faced a 17% lower risk of death than non-consumers (hazard ratio 0.83, 95% CI 0.72–0.96). This trend was statistically significant (P=0.0052).
Evidence grade: B
Sources:Dehghan M, Mente A, Rangarajan S, et al. (2018). Association of dairy intake with cardiovascular disease and mortality in 21 countries from five continents (PURE): a prospective cohort study. Lancet, 392(10161), 2288-2297. https://doi.org/10.1016/S0140-6736(18)31812-9
Notes: A key point of debate is that PURE included many participants from low- and middle-income countries; the fact that they could afford daily dairy intake suggests better socioeconomic status, which is hard to fully rule out as a confounding factor. Additionally, people with lactose intolerance can safely switch to yogurt or low-lactose milk instead of drinking regular milk.