Why would anyone with a serious disease want to be president? FDR had polio/JFK had Addison's. Don't know for sure what Hillary has. Isn't one's health/life more important than being prez?

The stress and strain of the job 24/7 is constant. Look at the presidents who have served and how they aged? Being prez is undoubtedly one of the most arduous and challenging jobs one can have if not THE MOST. It is a 24/7 job for 4 or 8 years.  You are never off the grid no matter where you are. I don't understand why some people would jeopardize  their health for that. Why do they?