Nowadays, we may know to avoid smoking lounges and we wash our hands after being in busy airports, but in the future, we may realize the key to health and happiness is improving our emotional immune system to protect ourselves from others’ stress. And of course, it’s not just other people’s stress that matters — our own mindset affects the happiness of those around us. https://hbr.org/2015/09/make-yourself-immune-to-secondhand-stress