I think 'old' is only one part of it. For me, it's health. Grim was a challenge, but still turned out OK. I have help, though. I think I could do one more without issue. Depends on how things go.... maybe I'll hold out longer than I think I will!
It also depends on the 'type' of pup. I'm just now trying dog sport, and I'm not at the top of my game. There are a couple of older people at the club I go to. Maybe the guy is who Lisa's referring to, IDK. It makes me happy that even the older folks will do what makes them happy!! Just have a plan... you always need to have a plan no matter how young you are!