It is better to do something oneself than to rely on others to do it well.

(rhetorical question, colloquial) Used to indicate that a previous comment is irrelevant or non sequitur.

Alternative form of damned if one does and damned if one doesn't

Two parts of an organization are unaware of each other's activities.

When finding oneself in a troubling situation, one should first make sure one is not making the situation worse by his own actions before addressing all other causes.

people who dispute that a task is possible should not impede those people who attempt to do it

(colloquial, sarcastic) A rhetorical question used to discourage the interlocutor from blind obedience.

Alternative form of if someone told you to jump off a bridge, would you do it

Synonym of if you find yourself in a hole, the first thing to do is stop digging

Do not procrastinate whatever that can be done today until tomorrow.