It is up to you to set expectations with those around you.
If you are a leader, this means setting expectations first and foremost with those you report to (upper management, executives, board). Expectations on what can be achieved, in which time frame, at what cost. Saying yes at all cost, whatever the reason for it, will just put you in a situation where all you can accept from those who report to you is a resounding and enthusiastic “yes!”. And a “yes” – perhaps not resounding, perhaps not enthusiastic – is all you are going to get. Ever.
It is the perfect recipe for failure.