Why smiling for your flu shot could keep you healthy throughout the season

When you know a flu shot is coming your way, you’re probably bracing yourself for the jab rather than dancing in circles with excitement. And it makes sense—who likes getting poked by needles anyway?

Well, according to a new study, it might be time to turn that frown upside down, because, reportedly, being happy on flu-shot day could make the vaccine more effective.

After measuring 138 people’s moods, physical activity, diet, and sleep three times a week for six weeks, researchers found the only factor that predicted how well the vaccination worked was the subject’s mood: The happier and more positive a person felt, the higher levels of infection-fighting antibodies they had in their system.

“A number of psychological and behavioral factors such as stress, physical activity, and diet influence how well the immune system works, and these factors have also been shown to influence how well vaccines protect against disease.”

Vaccinations’ “Achilles’ heel is that their ability to protect against disease is affected by how well an individual’s immune system works,” study author Kavita Vedhara, PhD, said in a press release. “We have known for many years that a number of psychological and behavioral factors such as stress, physical activity, and diet influence how well the immune system works, and these factors have also been shown to influence how well vaccines protect against disease.”

So if you’re feeling down the day your flu shot is scheduled—or just really, really hate needles—try spending some time with your super-positive friends before heading to the doc. Because, putting a smile on your face might just be one of the best (and easiest!) ways to fight off infection.

Here’s how you can boost your immune system using only your breath. And if you’d rather eat your way toward a flu-free season, stock up on these options.