Sometimes I think the world has gone completely mad. And then I think, 'Aw, who cares' And then I think, 'Hey, what's for supper'
- Deep Thoughts With Jack Handey

nnoble.

So do a Vipassana and you will have clear idea what it means "Don't Think too much"
The Tao quotation is well based in chinese culture

Don't think too much is absurdly simplistic and useless.

your thoughts highly influence your life. buddhism has the concept of "skillful thinking" and "thought pollutions".

"There are eight common thought pollutions: Envy, Greed, jealousy, anger... If we experience these thought pollutions, they can affect the way our brain functions and lead to varying degrees of depression which influences our physical, emotional, and spiritual health."

— The Tibetan Art of Positive Thinking by Christopher Hansard

If they tell you "你想多了" it may mean something else.

Good advice.

Thinking all the time is mentally very unhealthy. Its important to interupt your thinking with periods of thoughtlessness (without its normal association with selfishness or idiocy) whenever you can.

Good point Haali. But for some people, thinking at least occasionally would be an improvement.

I like the Taoist story, but I also think that 'being practical' - a Chinese virtue - can be overdone and can be merely another word for selfishness and sometimes for hopelessness and passivity in the face of Authority/Power in regard to the real possibilities of changing things for the better.
On the other hand, I sometimes think too much.

Y'all think too much...is that similar to the colloquialized propagation of Shakespeare's

"much ado about nothing"

(most certainly taken out of context) or

"making mountains out of mole hills"

etc ad infinitum?

I defy anyone to NOT think, or to control how much they think.
Even if it does seem that some people don't think at all, they do. WTF they may have been thinking is a different matter entirely. :-)

@tiger: try meditation for, not controlling how much one thinks, but allowing the thoughts to go away peacefully.