Do not take “When Breath Becomes Air” on the train for your next commute to work.

Do not pull out “When Breath Becomes Air” the next time you’re eating lunch at work.

Do not pack “When Breath Becomes Air” into your bag for your next trip.

It’s not that you don’t want to be seen with this book.

You don’t want to be caught anywhere in the open when you read “When Breath Becomes Air” because chances are great that you just might start ugly crying in front of a crowd.

Dr. Paul Kalanithi’s memoir is one of the most thoughtful, moving books you’ll read – perhaps ever.

Kalanithi was just months away from finishing his medical training as a neurosurgeon when he was diagnosed with stage IV lung cancer.

In a blink, physician became a patient. Despite all his medical training – which could be argued was more curse than help – he struggled to decide what to do next.

He’d imagined a long career as a surgeon, then another 20 years on top of that as a writer. Now he faced an accelerated timeline, his own expiration date looming – but when? It could be months. Or he could have five, maybe 10 years. Should he and his wife Lucy have a child? Should he continue working as a surgeon?

As he navigates these treacherous questions, he reflects on his life, his love of poetry and the path that led him to medicine. His writing is calming, inviting, taking you along this uncertain journey that includes a period of remission, a return to normalcy (of sorts) and then a crushing relapse.

And yet … This is not a depressing book. Kalanithi seeks meaning from his illness and comes to realize:

…the physician’s duty is not to stave off death or return patients to their old lives, but to take into our arms a patient and family whose lives have disintegrated and work until they can stand back up and face, and make sense of, their own existence.

The book is a brief, engrossing read, about 200 pages, and Kalanithi’s wife Lucy adds a coda describing her husband’s final days and how their family perseveres.

It’s tempting to call Kalanithi courageous, but that word doesn’t seem to do the man justice.

I read much of “When Breath Becomes Air” on my subway commutes to and from work.

That was a mistake.

By the time the author shared a message for his daughter Cady, who will never remember her gifted father, I had to close my e-reader and cover my face.

After finishing the book, I felt as if I’d lost a good friend. I mourn someone I’d never met, but whose writings connected us.

He reminds us: The only thing that’s certain from the moment of our births is that we will, one day, die.

“When Breath Becomes Air” opens the windows on the most taboo subject in our society and asks us to consider for ourselves what it means to have led a life well lived. How do we measure the quality of our own time?

Here’s a short video of Paul Kalanithi and his family. You’ll get a small sense of what an inspiring man he was.

You can get your copy of “When Breath Becomes Air” here. I can’t recommend this book enough.