Although I generally feel better when the sun is out, how much I smile or don't smile pretty much remains the same. Then again, maybe I make an unpleasant more when the sun is out.
Between having to squint, or having a headache because of too much sun, I spend a lot of time with a less pleasant expression on my face when it's sunny out. :) (I don't ever wear sunglasses because a) I hate the way they look, b) I hate to view the world through them, and c) I have the (perhaps unwarranted or even ignorant) concern that if I interfere with my eyes' chance to adjust to natural light I might face a "use-it-or-lose" kind of thing (if not now, at an older age). (By the way, it's a myth that squinting for years in adult life causes crow's feet. I've been using the squinting method for decades now - no crow's feet (although I can make some temporary crow's feet if I really, really, really, squint. :) ).