This long read by Joshua Wolf Shenk in the Atlantic is well worth the time. It is reminiscent of the 7-Up to 42-Up movies…
“Positive emotions make us more vulnerable than negative ones. One reason is that they’re future-oriented. Fear and sadness have immediate payoffs—protecting us from attack or attracting resources at times of distress. Gratitude and joy, over time, will yield better health and deeper connections—but in the short term actually put us at risk. That’s because, while negative emotions tend to be insulating, positive emotions expose us to the common elements of rejection and heartbreak.”