How many "lie downs" can you give a dog? If he hasn't lied down by the 2nd time you say it, you can best believe your correction is not hard enough. He is in the GREY zone and most likely crossing into the black. I went to a Bobby Dalziel clinic when i first started working BCs and he spent almost the whole clinic working on lie downs. :0)
If the horse is running away with you, you don't just give a few jerks on the reins; you need to do some something a bit more black and white, like lean back and turn his head into your knee. He needs to get the message. He needs to stop before you both get hurt.
Someone mentioned they didn't want their dog to become a robot when working with them. I don't think I have to worry too much about that. My BCs are too well bred for work. They usually will take care of things when I am wrong and they are right. That is NOT what I am talking about.
Champ is learning about Black and White right now. When I say "Come" it doesn't mean to dawdle around, sniff a few bushes and think about coming. It means COME right now. It also doesn't mean 'catch me if you can.' Lil Bugger! I'm making it REAL Black and White to him. When I say COME and he goes the other way, I HUNT him down without saying another word. If he turns towards me and starts to come, I back up and reward him. If he doesn't, it is fair game for me to give him a correction (one he will think about) when I catch up to him. 'Come' and 'kennel' have kind of flown out the window at almost 6 mos. of age. He thinks he is pretty cute. NOT! 'Come' could be a life-saver for him, so there is no GREY area.