Dave blogs about fifty phrases that kill creativity.
Some of these can I can and have identified with over time are:

We tried that before.
We don’t have the authority.
That’s not our problem.
I’m not saying you’re wrong but…
It isn’t in the budget.
It’s never been tried.
It can’t be done.
It’s too much trouble to change.
It’s impossible.
If it ain’t broke, don’t [...]