Every day I seem to spot a dog, white creeping over his face like a mask, who simply refuses to acknowledge his age. I think, "Careful! Don't dislocate that hip!" when I watch them bounce around like pogo sticks, and "Watch where you're going!" when I notice their eyesight is no longer 100%.
The truth is, dogs only get "old," mentally, if you let them--your best friend would stay young at heart forever if his body could keep up. The good news is you can help them stay alert, active, and healthy simply by encouraging that lifestyle. So don't quit now: they've got a lot more livin' to do.