You might find it superfluous or tiresome when friends share their times for their latest mile run on social media.
But a new study finds that it will actually motivate you: Exercise, it turns out, can be contagious.
The study examined exercise habits of more than one million runners across a five-year period.
"Knowing the running behaviors of your friends as shared on social networks can cause you to run farther, faster, and longer," study author and Massachusetts Institute of Technology professor Sinan Aral said.
Previous studies on health and lifestyle have found similar contagions for phenomena like obesity, anxiety and weight loss.
Pinning down this effect has limitations, though, like people's propensity for following others like them.
Plus, they included self-reported estimates from the people themselves on their eating or exercise habits.
The running was more contagious for men than for women, in that they ran longer distances or at a speedier pace if their male friends shared what they did.
The same goes for their female friends but it wasn't as significant.
On the other hand, women apparently didn't pay much mind to their male friends and nearly exclusively changed up their patterns only based on other women.