This research examined the effect of pre-post differences in walking duration, health, and weight on retirees’ long-term quality of life (QoL). It used data from a 2018 randomized mail survey of 483 suburban New Jersey retirees. Ordinary least squares (OLS) and three-stage least squares (3SLS) models were used. The analysis showed that changes in walking duration during the first two years of retirement are directly associated with health change, health change has an effect on long-term QoL, and weight variation of 10 lbs or more has an effect on health change and long-term QoL. Although QoL peaks for the sample of retirees at around age 75, people whose average walking duration increased, health improved, and weight did not increase substantially after retirement continued to experience high QoL for a longer time. The results show that people can achieve high long-term QoL by choosing an active lifestyle when transitioning to retirement.