I don't remember ever smiling much when I was sad, but your question did trigger a memory that illustrates the power of a split second contact between two Souls to have powerful results.
In January of 1981, I was not a happy camper. My third wife was turning out to be tough to live with, our finances were in desperate straights, and for the first (and only) time in my life that I can remember, I was truly despondent. Even considered suicide once, though only briefly.
One Sunday, she and I were walking down the sidewalk in Billings, Montana. Don't remember why (we lived miles north of the city), but do remember very clearly how heavily burdened I felt. Every step was a challenge, the weight of the world pressing down on my shoulders.
Coming toward us, the only other people on the street at the moment, were a little girl--I'd guess about 4 years of age--and her mother. The child and I made eye contact, just for a second...she smiled (I presume I did, too), and twin beams of the purest Light and Love shot from her eyes straight into me. All. The. Way.
Uplifted me unbelievably.
Not enough to magically "cure" my depression completely; it was too ingrained for that. But it was a start, and something I've never forgotten.
The (now ex) wife walking beside me never had a clue nor, I'm sure, did the little girl's mother.
There's always a way out...if we can see it.