Reviewing the Happiness Advantage by Shawn Achor. This book unlocks potential for happiness, in every area. Many of the research studies cited also talk about one key factor being a part of an enjoyable life: PLAY, and enjoyment.
Links to the book:
https://www.amazon.com/Happiness-Advantage-Positive-Brain-Success/dp/0307591557/ref=sr_1_1?crid=37MVNJUN79DE9&dchild=1&keywords=the+happiness+advantage&qid=1614968878&sprefix=the+happiness+%2Caps%2C380&sr=8-1