Fools who wear their hearts proudly on their sleeves, who cannot control their emotions, who wallow in sad memories and allow themselves to be provoked this easily - weak people, in other words.Severus Snape in Harry Potter and the Order of the Phoenix
I think you should take your job seriously, but not yourself - that is the best combination.Judi Dench
Take your work seriously, but never yourself.Margot Fonteyn
In other words, you don't want to be serious
It takes two to be serious.