Those years will be coming up to him before he even realises they have passed him by. Though, to be fair, it is still too early to say which path is the right one to follow. The end has to come first in order to determine whether it will have all been worth it in the end.

"Wyatt Earp wanted to be a farmer. He could not abide the violence, the bloodshed. But it was not to be." And John Henry Holliday wanted to be a dentist. That was not to be, either. He is here now, smoking on a porch a hundred and sixty something years later. And Wyatt is long dead and gone. Doc never blamed him or felt resentful for having to do his dirty work when he couldn't stomach it, for cleaning up after his messes all those times he shot, got cold feet, and ran away. He would always be a dear friend, and Doc doesn't feel the need to dig all that ancient history up now.

"The OK Corral damned us all." Doc closes his eyes and lets his cigarette hand hang loosely by his side, flicking ashes off with a few swipes of his thumb.

"Knowing what I know now, what happened to his children and his children's children, if I could take it all back, I--... hell I would have kept my practice open, bought him that damn farm myself, sent him there." So, yeah. If he can save one marshal several lifetimes of agony, he will. And if he can't, then at least he's tried his damnedest best.