"Many people work hard...
...the successful ones are the ones who work intelligently."
I phrased it earlier (in the The productivity trap) this way:
"WHAT to do and HOW to do is more important than the amount of things you achieve."
Or again in other words:
"It is not enough to work hard, it is important to work on the right thing in a good way."
An old phrase also says: "Switch on your brain before you do something."
In the last weeks I have seen pretty good examples where people worked hard on solutions where the goal could have been achieved better and easier by thinking simpler and different.
Another phrase says: "It's lonely in the saddle since the horse died."
Related posts: The productivity trap, Dynamic activity, Get focused with 3 questions, Responsibility and decision.