Other studies, including a comprehensive analysis of elections dating back to the 1700s, have found that heading a nation can take years off a leader’s life. The analysis, from the Harvard Medical School, found that elected heads of government, on average, had lives almost three years shorter than those of the candidates they defeated.
https://www.nytimes.com/2015/12/15/health/leading-a-nation-takes-years-off-life-study-suggests.html
I know that some (like Jay O) disagree—see https://www.history.com/news/do-u-s-presidents-age-faster-while-in-office—but it takes an unusual degree of mid-life fitness/robustness to even be elected president at later ages (which are the ages that people are more likely to be elected, at this point).