You know how, sometimes, you start being tooooo proactive and implement stuff even though your boss never told you to do it? Well, that happened at my previous job, and apparently almost everyone at the team questioned the changes and made me look like the fool I was. That day, I learned that you should never implement stuff that wasn't asked... And it was humbling, since I was an arrogant fuck and basically I was speaking loudly and denied the criticism... But today, I'm better, I know how and when to shut up, and I accept criticism now.