Resting bitch face

So sometimes I find myself with a bit of a problem at work. I try my best to not go in a bad mood but my face just insists on telling the world that I am mad or tired. It's gotten me in so much trouble before. I usually get the comments "oh it's been a long day" or "why are you so mad" I'm really not mad that's just the way my face is, or i'm so concentrated on getting my work done that that's just the way my face appears. It's always been one of my biggest pet peeves and it automatically puts me in a horrible mood! it's ridiculous! I've never had the nerve to ask someone that. As a customer i'd just get my stuff and be gone. So the next time you wanna ask your cashier if she's mad consider tjat maybe that's her face, haha