One of the natural impacts of aging is an increase in frailty. Injuries do not heal as quickly as they once did. People do not recover quite as fast. Injuries that they once would have considered minor now take a larger toll.
There is nothing that can be done to avoid this process entirely; even someone who works hard to stay in excellent shape is eventually going to see an increase in frailty and vulnerability. Experts note that this is because of a "cumulative decline in multiple physiological systems over a lifespan." This means that a relatively minor event can "trigger disproportionate changes in health status."