This book is oddly named. Judging by its cover, you might think it should be more of a self-help text. But in actuality, it's much more of a philosophy text.
The whole work is structured as a dialogue between an old teacher and a young student. The student is well-read in philosophy and psychology, but full of problems. The core perspective of the book comes from Adlerian psychology, a theory of being first created by Alfred Adler.
It's quite a bit different than other works I've read, in that while it's non-fiction, none of the characters are named. I found it incredibly thought-provoking, and a lot of the concepts which I haven't heard elsewhere really resonated with me.
Humans aren't governed by causes, but goals
Most psychology tends to look at inputs: what was your relationship with your parents like growing up? what things did you do as a child? What has driven both your past joy and sorrow? All of these inputs are used to predict and explain behavior of the individual.
Adlerian psychology takes a different approach. It states that all people are governed not by their past, but by particular goals that they have. A core believe is that everyone is able to change... but they don't because the change somehow counteracts their goals of being comfortable.
When viewed through this lens, human behavior takes a very different shape. When someone gets angry, the question isn't "why did they get angry?", but "what are they trying to achieve?". I've found it to be a much more useful lens when it comes to explaining behavior of individuals. When someone says "I can't achieve X", it's useful to examine why. What is the unspoken goal which is holding them back?
All problems are relationship problems
Another interesting idea is that fundamentally, all problems that we encounter today are relationship problems. If you were the only person on earth... you'd have no one to compare to. You wouldn't find yourself uglier or less wealthy or less accomplished than anyone else, because there would be no comparison.
Ultimately true happiness first comes from self-acceptance and being happy with one's self. If you constantly compare yourself to others, you'll consistently be unhappy.
The book also puts forth some interesting theories on relationships: that it is better to have a few deep friendships than many shallow ones, that most relationships you ultimately choose with the exception of your parents, and that with most people, you will either like or dislike people depending on the goal of interacting with them.
Courage makes the difference
The sole difference-maker of change is the courage to change. In a given case, the change may feel hard and uncomfortable, but the way to solve for it is through diligent work and practice.
An example given in the book is of a man who wants to become a famous novelist. Year after year, he claims that he wants to be a writer, but never ends up actually submitting his works. In this case, he holds on to the idea that he could become a famous novelist if he tried, rather than actually taking the courage to push forward, and possibly be rejected.
We desire community feel
What creates true happiness is the feeling that we provide value to others in the community. This is most obvious in terms of work, but can take place simply by existing. It's the reason why the exceedingly rich take part in philanthropy or continue to work even when they do not require it.
Imagine a group of 10 people. 1 will dislike you no matter what you do. 2 will like you almost unconditionally and get along fabulously well, 7 will be ambivalent. Who do you focus on? The 1, the 2, or the 7?
What's interesting here is that new initiatives like Universal Basic Income still have to solve for the problem of self-worth. If I'm not required to work, how can I instead feel my value to society?
Strive for horizontal relationships
It's easy to view some relationships as 'vertical'. Where you see the other person as inferior or superior to you. These are unhealthy. Instead you want to strive for 'horizontal' relationships. You treat other people as peers, without caring about what they think.
I've heard PG talk about his kids this way. That the best way to treat them is by thinking of them as adults.
Separation of tasks
A last idea is separating tasks. It is for you to change the things that you can, but not worry about other people's thoughts and opinions (it is their tasks to feel that way).
This means that when dealing with a child or pupil, Adler preaches that we should not attempt to do their task for them, but rather to let them accomplish it on their own. We may help and support others, but fundamentally should not confuse which tasks are theirs vs which are ours.