This observational study investigates whether the provision of ongoing short-term-incentives for verified physical activity increases and sustains levels of physical activity. We compared UK members at baseline (years 1 and 2) prior to Vitality’s Active Rewards (VAR) intervention commencing (year 3) and follow-up (year 4) for verified, self-reported (encompassing additional physical activities), mortality relative risk and satisfaction with physical activity. Members were categorised into low-active, medium-active and high-active by tertiles of baseline physical activity. Of 11,881 participants, 6477(54.5%) were male, with mean age 39.7(SD 9.8) years. At follow-up, annual active days had increased by 56% overall [60.8(59.7–61.9)–94.8(93.0–96.5)]; 554% in low-active [8.5(8.3–8.7)–47.1(44.7–49.5)]; 205% in medium-active [39.8(39.4–40.2)–81.4(78.7–84.1)] and 17% in high-active members [131.7(129.9–133.5)–153.7 …