I wanted Earl to use his scratching post rather than destroy my furniture. So each time he used the post, he'd get a treat.
Then, when he started to go outside, I'd reward him with a treat each time he'd come back in when I called. He'd saunter in, go sit by the scratching post, and I'd give him his reward.
Later, when he'd come in from outdoors, whether or not I'd called for him, he'd still expect a treat. Always administered by the rarely-used scratching post.
Now, he just wanders over to his "treat spot" when ever he feels like it. And sits there. Patiently. Looking adorable. And invariably, his cuteness and patience wears me down, and he gets the treats he's waiting for.
The trainer has become the trainee, apparently.