By any measure, Cy Young is one of the greatest pitchers in baseball history. His 511 career wins are a record that will probably never be broken, at least not during our lifetimes. He also is the all-time leader in starts (815), complete games (749), innings pitched (7,356) and pitcher WAR (168.4). There's a reason they named the award after him.
Of course, Cy Young pitched a long time ago and baseball was a much different game back then. Pitchers haven't endured that kind of workload in decades. Cy Young pitched for five teams from 1890-1911 but spend the majority of his career with the Cleveland Spiders. He lived until 88, and, a year before his death, he participated in an Old Timers' Day event:
Cy Young at 87 at an old timers game. pic.twitter.com/OeM2AiVNg5— Just Baseball Photos (@Baseball_Photos) December 28, 2013
He looks like he could have gone out and thrown both ends of a doubleheader that afternoon.