How do you keep it fun AND professional?

I think it comes down to respect and clarity of roles. You can absolutely have a relaxed environment and joke around. That is part of working side by side in the field. At the same time everyone must understand when it is time to focus and move the job forward. For leadership roles I believe in keeping clear lanes. Managers should not jump into client conversations unless that is their responsibility. When that happens, it breaks communication and creates confusion. The chain needs to stay consistent. As far as the crew goes, I am friendly with everyone, but I keep a professional line. I want the team to know I am approachable, but also that it is my job to set expectations and keep the company moving forward.