Anyone have any advice for combatting resting bitch face in a professional setting?

My company is going through a “brand refresh,” and last week we had a daylong training session about the new voice/tone we need to take in communications. It was primarily writers — my supervisor and I were the only editors.

I thought the meeting went really well, and I’m excited about the changes (basically it boils down to sounding a lot less stodgy and corporate, which I love). But apparently the outside company that developed the brand voice and did the training told the head of our department that “the editors” had been really resistant to change and and very negative about the whole thing, and that the training sessions without editors had gone much more smoothly.

My supervisor didn’t speak much at all, and when I spoke it was to express enthusiasm, so the only thing I can think is that is that I/we “looked” unhappy and uncooperative.

This is kind of a big deal — the brand changes are a major part of the company’s focus and my department’s job, and being perceived as being hostile could have serious negative repercussions — so it’s something I need to make sure doesn’t happen again.

I keep flashing on Tom Haverford screaming, “Make your face better!” I have no idea how to go about making myself look happier when I’m concentrating or not actively smiling. That’s just how my face looks!