Your smile could be a self-fulfilling prophecy.

• Why it matters: Simply smiling when you're stressed or blue can lift your spirits, research shows — even when you don't totally feel it.

🔎 Zoom in: Several studies have found evidence that the physical act of smiling can boost feelings of happiness.

• People who smile while performing stressful tasks tend to have lower heart rates than those with neutral expressions, Judy Ho, a Los Angeles clinical and forensic neuropsychologist, told AP.
• Smiling while running can help you relax and run more efficiently, Outside Magazine reports.

The intrigue: The findings support the idea that physical actions and sensations can help shape emotions, rather than simply reflect them, Stanford researchers write.

• A smile, even a forced one, can make us feel happier. A furrowed brow can spark feelings of anger.

🎒 Case in point: At the Orange County Academy of Sciences and Arts in Southern California, the power of a smile is taken very seriously. An entire section on the charter school's website is dedicated to its philosophy that a smile can make a difference.

• "Smiling creates a supportive classroom culture that makes students relaxed, active, and motivated," according to the website. "It increases emotional well-being, lowers stress, and gives students confidence."

Smiling isn't a magic fix. One analysis of 138 studies found that the emotional benefits of facial expressions are modest and vary depending on the circumstances.

• But it's a free, instant tool to keep in your back pocket next time you're feeling down.

Go deeper.

A random act of wintertime kindness, shared by reader Joan Orman of Galesburg, Mich.:

• "The temps were hovering around 20°, and it was past dark when I stopped off at a Kmart store on my way home from work. I was on my bicycle, a little over 4 miles from home. As I exited the store, I realized that I didn't have my big puffy gloves with me. Remembering that I'd set them on a bench to lock up my bike, I was quite dismayed to see that they were no longer there."
• "This would not be a good ride home. As I got closer to my bike, I saw that some kind passerby had noticed the gloves, balled them up and stuck them in the water bottle cage on my bike. That angel saved my digits!"