Drawings Featuring Closed-Eyed Smiles - Nothing Beats a Simple Grin
The downward arc used to depict closed eyes when smiling is not only a staple in the world of anime and manga, but it's also one of the first things many fledgling artists master when creating their own characters. It's a simple way of bringing a bit of joy to your art.
Galleon (from Granblue Fantasy) looks as though she's serenely taking in the sounds around her, doesn't she?
Have a look at the illustrations and see if any of them lift your spirits.