Buster Keaton was trained in the art of physical comedy from childhood, routinely being thrown around on vaudeville stages by his father (who would also throw him at the occasional heckler in the audience) and was supposedly once required to strip naked in front of the mayor of New York in response to a child abuse charge.
When making movies, he would typically be doing his own stunts, everybody
else's stunts, as well as acting, directing, and coming up with scripts requiring a multitude of insane stunts. The cameraman would typically be told to keep shooting until Keaton yelled 'Cut' - or was killed.
During the making of his most famous movie,
The General (1927), set during the American Civil War, Keaton initially insisted on using wood as fuel for the actual 1860s locomotives involved. Unlike coal, which by then had been the norm for as long as anyone could remember, wood caused embers to fly from the locomotive's smokestacks, starting a serious brushfire - which was swiftly brought under control by local volunteer firefighters under the personal leadership of Keaton.
When asked how he could do all that crazy stuff without showing signs of pain or injury, Keaton simply removed his shirt - showing off a massive collection of scars and bruises. This was his only secret: He cared more about the comedy than about not getting hurt.
He actually broke his neck once. And survived. And didn't notice. Just another day at work.
"I'm not very good at public speaking, so to show that my heart is in the right place, I'll fight any man in the house."
[small]-Buster Keaton, responding to a toast in his honor at the celebration of his 69th birthday.[/small]
Yeah. And he was about 33 when <that avatar picture was taken.
I'm 33 now.
I lost the fight the day he was born!