DS is 17 months and your average mischievous toddler. He is bright and into everything and understands a great deal. So the the course of exploring his world he does things we don't want him to do e.g. splash his hand in the cat's water bowl, climb on things where he might fall, go round the back of the TV set and pull the cables etc. We have childproofed the house as far as possible but there are some things we can't move / block access to, and we just have to control him.
So here's the problem. I say NO very firmly and sternly but trying not to shout. I look sterm. He laughs or shakes his head with a cute gleam in his eye (so very hard for me to keep a straight face) and persists in what he is doing. I try distraction - he has a good concentration span and will not be distracted. I forcibly remove him and try distraction - he runs straight back to what he was doing. He gets LOTS of praise when he stops doing the naughty thing and does something else, but he still likes to do the naughty thing.
I don't want to resort to shouting or smacking, but I have on occasion smacked his hand when he has been touching something dangerous and all other attempts to stop him have failed. He hasn't been bothered by this (obviously I didn't smack him very hard!)
He doesn't seem remotely bothered by me or his dad telling him off, he just ignores us. How can I make my discipline more effective without losing my temper?