“Life isn’t as serious as the mind makes it out to be”

If you are interested in the topic of the egoic mind, might I recommend, A New Earth, or The Power Of Now by Eckhart Tolle. I know you asked for one book, but they are primarily analogous.

A small sample of Eckhart Tolle quotes:

“The past has no power over the present moment.”

“Some changes look negative on the surface but you will soon realize that space is being created in your life for something new to emerge.”

“The primary cause of unhappiness is never the situation but your thoughts about it.”

“Acknowledging the good that you already have in your life is the foundation for all abundance.”

“Life will give you whatever experience is most helpful for the evolution of your consciousness. How do you know this is the experience you need? Because this is the experience you are having at the moment.”

“Realize deeply that the present moment is all you have. Make the NOW the primary focus of your life.”

“Sometimes letting things go is an act of far greater power than defending or hanging on.”

“To love is to recognize yourself in another.”

“Life isn't as serious as the mind makes it out to be.”