This has to be an art. Because people are people! No one is happy all the time.
I'd look at a famous actors or actresses. Their job is to play a role. Whether they are happy, sad, mad, scared or not.
The famous actor acts, finishes the movie/show production and then goes home.
Johnny Depp as Captain Jack Sparrow doesn't show up angry at his cousin or wife or cab driver. He shows up as a drunken pirate. Savvy?
Actors were given a tool called "Method acting". It was adopted in Hollywood decades ago. It was a game changer in the industry. Google search that? Olivia Cabane wrote about this, and has some insight.
All I can say is I'm a real person, with real emotions. The pros are really good at hiding their bad days. That's why they are pros and making the big bucks. Sometimes it's just easier to take a day off (or more if you need it!)