On January 20, 1945, Franklin Roosevelt was inaugurated to a fourth term. He was so weak that he gave the inaugural address from a porch in the White House. Artist Jo Davidson designed this official inaugural medal which marked the event. It reflected FDR's true physical condition. Yet his campaign buttons made him look like this in 1944. FDR's doctors knew that he could not survive a full fourth term because of his heart. Yet FRD ran for a fourth term. Fortunately the party leaders had the good sense to replace far leftist, Henry Wallace, with Harry Truman. Currently modern Democrats are facing the same situation with Joe Biden. He's too old and not healthy enough to serve another term.
Biden is much healthier than Trump. Trump is obese. 80 year old obese men don't have long left. Biden might live well into his 90s. They are both too old to be president. They have been too old for at least 10 years. it has nothing to do with their health.