Eight of the ten things you have decided about yourself at the age of twenty will, over time, prove to be false. The other two things will prove to be so true that you’ll look back in twenty years and howl.

At the age of forty the life you have lived so far, always pro tem, has for the first time become life itself, and this reappraisal swept away all dreams, destroyed all your notions that real life, the one that was meant to be, the great deeds you would perform, was somewhere else. When you were forty you realized it was all here, banal everyday life, fully formed, and it always would be unless you did something. Unless you took one last gamble.

Though actually I think that being in one's twenties is in itself to be restricted. At that age one's vigour is great, and one looks ahead, keeps one's eyes fixed on things to come, and of the things found in one's surroundings the most important are always those that hold the most promise. At the same time, and this is the cruelty of it, this forward-looking gaze is constantly confronted with the limitations of one's character, constantly coming up against a sense of stagnation - hence the youthful fear of stagnating intellectually.

While this is obvious, it is something that most people to a greater or lesser degree choose to ignore. They ignore it because our route to reality is not easy. First of all, we are not born with maps; we have to make them, and the making requires effort. The more effort we make to appreciate and perceive reality, the larger and more accurate our maps will be. But many do not want to make this effort. Some stop making it by the end of adolescence. Their maps are small and sketchy, their views of the world narrow and misleading. By the end of middle age most people have given up the effort. They feel certain that their maps are complete and their Weltanschauung is correct (indeed, even sacrosanct), and they are no longer interested in new information. It is as if they are tired. Only a relative and fortunate few continue until the moment of death exploring the mystery of reality, ever enlarging and refining and redefining their understanding of the world and what is true.

… if you knew the mess my life was in … the waste of it … the uselessness of it. I have no moral purpose, no real sense of duty to anything. It seems only a few months ago that I was twenty-one – full of hopes … all disappointed.

There are some things you can't understand yet. Your life will be a great and continuous unfolding. It's good you've worked hard to resolve childhood issues while in your twenties, but understand that what you resolve will need to be resolved again. And again. You will come to know things that can only be known with the wisdom of age and the grace of years. Most of those things will have to do with forgiveness.

When you're 20 you care what everyone thinks. When you're 40 you stop caring what everyone thinks. When you're 60 you realize no one was ever thinking about you in the first place.

Spending your twenties traveling four days a week, interviewing employees, and writing detailed reports on how to cut costs will change you, as will spending years editing contracts and arguing about events that will never come to pass, or years producing Excel spreadsheets and moving deals along. After a while, regardless of your initial motivations, your lifestyle and personality will change to fit your role.

Between the ages of twenty and forty we are engaged in the process of discovering who we are, which involves learning the differences between accidental limitations which it is our duty to outgrow and the necessary limitations of our nature beyond which we cannot trespass with impunity.

At age 20, we worry about what others think of us. At age 40, we don’t care what they think of us. At age 60, we discover they haven’t been thinking of us at all.

... In your twenties you're becoming who you're going to be and so you might as well not be an asshole. Also, because it's harder to be magnanimous when you're in your twenties, I think, and so that's why I'd like to remind you of it. You're generally less humble in that decade than you'll ever be and this lack of humility is oddly mixed with insecurity and uncertainty and fear. You will learn a lot about yourself if you stretch in the direction of goodness, of bigness, of kindness, of forgiveness, of emotional bravery.

There's a point, around the age of twenty, when you have to choose whether to be like everybody else the rest of your life, or to make a virtue of your peculiarities.

You’ll be fine. You’re 25. Feeling [unsure] and lost is part of your path. Don’t avoid it. See what those feelings are showing you and use it. Take a breath. You’ll be okay. Even if you don’t feel okay all the time.

Life really does begin at forty. Up until then, you are just doing research.