Shortly after my boss gave me some pretty harsh feedback that I very strenuously disagreed with and felt was based on some faulty assumptions. I fought back my impulse to immediately push back and started by thanking him for the feedback, then focusing on why he felt that way and how I could change that view.

Four months later the company made a bunch of cuts and I was coincidentally one of the affected. Kind of soured me on the whole "Feedback is a gift" mentality.