Joe Biden was born in 1942, making him the oldest president to ever take office. If he is elected to a second term, he would start it at 82. There have been a number of rumors and specualtions about his health, with many conservative pundits claiming he is suffering from dementia. On the other hand, routine medical check-ups describe him as "vigorous":

https://apnews.com/article/biden-politics-united-states-government-health-bdce6c15df6186e06710f2d903a3513e

Doctor says Biden's 'vigorous' as he readies for 2024 run

Despite testing positive twice last year for the coronavirus, President Joe Biden has no long-term symptoms and has been declared “healthy, vigorous” and “fit” to handle his White House responsibilities.