In the third episode of season 5, Secret's Safe With Me, Richard finds a little doll in Kate's desk drawer. He's intrigued by it and wonder why she has it. Finally, near the end of the show she explains:
Kate: Coney Island. We had a reception at our place after my mom’s funeral and it was miserable.
I was miserable and my dad took my hand and he said, “Let’s get the hell out of here, Katie.”
And we took the Q-train and we went up to Coney Island. And we walked up and down that beach just enjoying ourselves. We were still in our funeral clothes. And the best part was that we made this little guy out of the twigs and twine that washed up on the shore.
Richard: Does that make that day a bad memory, or a good one?
Kate: Both. He’s reminder that even on the worst days, there’s a possibility for joy.
About a hundred years or so ago GKC had something to say on the subject as well in Orthodoxy.
The mass of men have been forced to be gay about the little things, but sad about the big ones. Nevertheless (I offer my last dogma defiantly) it is not native to man to be so. Man is more himself, man is more manlike, when joy is the fundamental thing in him, and grief the superficial. Melancholy should be an innocent interlude, a tender and fugitive frame of mind; praise should be the permanent pulsation of the soul. Pessimism is at best an emotional half-holiday; joy is the uproarious labour by which all things live.