Read the HBR article; not this book.

The concept of emotional agility (essentially, an ability to moderate and be aware of your emotions combined with a practice of resiliency) makes sense. This book, however did not. I found the style of writing to be worthy of eye-rolling. The author doesn't make many substantiated arguments, and more often than not parrots other popular works (Viktor Frankl, Angela Duckworth, Carol Dweck etc.).