My dog's older and better trained now. She'll heel pretty well, and she will sit in front of her filled food dish until told "O.K." You can leave her there and she'll wait til you get back (I just go around the corner, making her wait for her supper just for grins is cruel!) or you can put a biscuit on the ground in front of her, tell her "leave it", and she will turn her head so she doesn't have to stare at it, but she won't touch it til you tell her "O.K."
But she still is a sucker for human interaction. She'll still break sit if somebody speaks to her. We're working on that. For a loony Chocolate Lab she isn't doing so badly . . .