Don't remember exactly when was the beginning, but doing it for a living since 2001.
Biggest takeaway from all these years:
- strive for learning more, every single day.
- be conscious that you might become good, or even an expert, in a given topic, but even then you don't know everything about it and should listen to others and continue reading/learning/listening
- any good teamwork is based on a super stupid simple principle: say what you plan to do, and do what you said. From there come the discussions, it helps avoid the pitfalls, it helps having better interactions, ...