Hm. Well, riddle me this:
Thor is excellent at Stay, as long as there is no one around him. He can Stay for over a minute if we're in a calm area. If there is another dog or person, or say, a paper bag, he gets up. I've been trying to practice Stay with him quite a bit (minimum is 5x/day). I'd like him to sit at corners, while I am waiting in line, etc. The thing is, he is so small that I feel like to some degree he's right to be so nervous. One stray human foot, and he will go flying. On the other hand, he is overly nervous. I'm pretty sure he is not going to be harmed by a paper bag, for instance. Sometimes he just breaks the Stay because he sees something very interesting he wants to check out. Also, if he's not Staying, he's off exploring, trying to climb up people's legs and generally being a Bad Doggy.
I try to put him in Stays in a position where he can feel safe, like with his back to a wall. But I'm kind of wondering if I am being counter productive, because now he is breaking Stays all the time, and I don't want him to think it's optional.