Our dog Mercury is so clever! Angelica got him for her fifteenth birthday and is supposed to do his training, but she never taught him more than the sit command. Later, I taught him to lie down when I said, "Down," and it only took him a few minutes to learn and remember it. (Border collies are smart!) Well, she still hasn't taught him anything else, so I decided to work with him again. I taught him "Stay!" and "Come!" And again, it only took a few minutes to teach him. (Of course, there were no distractions around such as other dogs to play with.) He is so EASY to train.
Now I just have to teach him to run with me without grabbing his leash and pulling while jumping around in front of me growling playfully. Right now, whenever I try to run, he thinks it's a game.