And then do it.

"It can't be done." "It would never work." "They won't let you."
As long as this is the answer to someone's idea, then it can't be done.
If your answer is, "This is a good idea. Let's think about how we can do it." then chances are much better.
If I had an employee who led off with "It can't be done." I'd fire his ass.
How many people said that heavier than air flight couldn't be done?
How m any are saying we'll never exceed the speed of light? I never will, even though I have no idea how it could be done. One day, someone will do it.