The message I got was that he starts off with his life in perfect order and discipline but he's empty inside, lonely, disconnected, numb. He doesn't even realise it. He's become cold, detached, used to it.
Then his subconscious attacks. He has a massive panic attack. Psycho-somatic symptoms and physical pains, no physical signs for a diagnosis of any physical cause of ailment. It's psychological. It throws him out of his strict routine, and in his disoriented state he does something out of character. He wanders into a doughnut shop in the early morning hours upon leaving the hospital.
There, his journey starts into chaos, finding new connections, mending old ones. He starts living life. It's messy, it's awkward, it doesn't make sense. But he's enjoying it.
In the end, everything's a disaster surrounding him, carnage, catastrophe. Yet, he's peaceful, he's connected, cared for and caring of others, and he's present, he's fine, he's calm. Why? Because he's found himself in connecting with others.
For me, the message is that it's better to be connected to others even if life isn't simple or straight forward, because it makes you confident and content. Connection is better than having your life in a perfect routine and discipline, all in order but totally disconnected from others, from humans, from emotions.
This book is the transformation from where everything appears perfect on the outside but there is fear and anxiety on the inside, to where everything is chaos on the outside but on the inside there is calm, confidence, contentment. The bridge between the two alternative states of existing is - connection.
That's it.