i think too much discipline would involve directly hurting
a child's ego - or like someone else said, lowering their
self-esteem. maybe reflecting on your own childhood and
discipline &remembering how certain things made you
feel, will help you to better understand your own children...
i remember a lot of times, my punishment was a week
without the computer. to me, this was the harshest!
think about if you took the cell phone away? its amazing
the remorse that can be felt when denied something
we "love" in light of a wrong we've caused. a lesson
teaches itself, rather than a lecture from mom or dad,
in which they're half-listening anyway.
treating kids like their opinion matters, maybe? talking to
them about exactly why they're being punished - and
enforcing it. not just throwing around "you're grounded!"
every time something comes up and by the next day,
everyone's forgotten about it, or you feel guilty and end
up letting it go. this only teaches them that they can do
it no matter what &you don't really mean what you say.
i don't have kids but i watch a lot of supernanny, and i've
always wanted to be a child psychologist or something

lol.
hope this helps...