Is their anything that you can do a lot and then not really suffer too much from it?
Breathing.
Oh, wait, you keep up that oxygen habit and you’ll die sooner or later. 
Seriously, though - even an excess of pure water is dangerous. So I would say yes, everything has to be taken in moderation.
Since “too much” is typically defined as “enough to be bad,” then yes, I’d have to say that too much of anything is a bad thing.
On the other hand, if you’re asking “is there anything for which it is impossible to have ‘too much’?” then that’s an intriguing question. Just off the top of my head, I’d say no.
I dunno, too much death kinda sucks…
Hard disk space?
“Well of course too much is bad for you. Too much of anything is bad for you, you blithering twat - that’s what too much means. Too much water would be bad for you. Obviously, too much is precisely that quantity which is excessive - that’s what it means!”
- Stephen Fry
You can never have too much bandwidth.
Too much moderation.
Nope. Too much moderation and you never get to enjoy really, really great things, which by definition are not moderate. Too much moderation is bland and boring.
Too much Straight Dope?
Which leads us to my favorite Lazarus Long quote:
Moderation in everything, including moderation.
(Especially appropriate for moderated forums… 
)
Oops, hit submit instead of preview.
AFAIK, there’s only one thing that you can’t “overdose” on: knowledge. (Homer Simpson quotes notwithstanding.)
As in, “Marge, every time I learn something new it pushes something old out of my brain.”
You’ve never heard the expression, “Too smart for your own good.”?
That is not true, you can never be too smart. Information must be taken in moderation, but I do not think there is any real limit.
Maybe you are thinking of talking too much while being very smart.
No, I’m thinking where the hero figures out the villians clever plot, catches the villian in the act, and the villian says, “You’re too smart for your own good.” At this point the villian attempts to kill the hero, but the spunky sidekick who’s been bumbling around off-scene chooses this moment to show up and clutzily manages to save the day.
“Too much of everything is just enough.” - Jerry Garcia
But remember knowledge, intellegence, and maybe even cunning aren’t quite the same. You can easily regret knowing something: goatse. You could regret being intellegent: isn’t it traditional that stupid people are happier?
Nope.
I’m above average intelligence (according to blah blah blah…) and I’m very happy. Some of my frinds are not too bright at all, and all in all, they’re not too happy - boring jobs, no spare cash, crappy holidays.
I dunno about everyone, but for me intelligence = happiness.
YMMV of course…
Too much water…aside from drowning…can dangerously dilute your electrolytes.
In a hyperbaric chamber…y’know, the thing Michael Jackson sleeps in 
…pure oxygen above three atmospheres is toxic.
Too much knowledge could be a bad thing. I can think of two different ways:
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one has to look at the opertunity costs. If you spend all your time seeking knowledge, you miss out on life, friends, etc.
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if you friend tells you he has killed someone, having that knowledge can send you to prison as an acompliss (sp?). In that case, I would say you had too much knowledge, and it was a bad thing.
So I am in support of those who say “too much of ANYTHING is bad.” All depends on your definition of bad though. Some might argue that just because you go to prison maybe it was still worth knowing. After all, then you get the chance to know what living in prison is like, and if you are truly only concerned with seaking knowledge, that might not be such a bad thing.
I doubt you can have humans doing too much to help each other.
Too much technology and knowledge doesn’t sound bad either, unless someone blows up the world.