1. You realise that most of the bad behaviour of other people really comes down to fear and anxiety – rather than, as it is generally easier to presume, nastiness or idiocy. You loosen your hold on self-righteousness and stop thinking of the world as populated by either monsters or fools. It makes things less black and white at first, but in time, a great deal more interesting.

2. You learn that what's in your head can't automatically be understood by other people. You realise that, unfortunately, you are going to have to articulate your intentions and feelings with the use of words – and can't fairly blame other people for not getting what you mean until you've spoken calmly and clearly.

3. You learn that – remarkably – you do sometimes get things wrong. With huge courage, you take your first faltering steps towards (once in a while) apologising.

4. You learn to be confident not by realising that you're great, but by learning that everyone else is just as stupid, scared and lost as you are. We're all making it up as we go along, and that's fine.

5. You forgive your parents because you realise that they didn't put you on this earth in order to insult you. They were just painfully out of their depth and struggling with demons of their own. Anger turns, at points, to pity and compassion.

6. You learn the enormous influence of so-called "small" things on mood: bed-times, blood sugar and alcohol levels, degrees of background stress and so on. And as a result, you learn never to bring up an important, contentious issue with a loved one until everyone is well rested, no one is drunk, you've had some food, nothing else is alarming you and you are not rushing to catch a train.

7. You give up sulking. If someone hurts you, you don't store up the hatred and the hurt for days. You remember we'll all be dead soon. You don't expect others to know what's wrong. You tell them straight and if they get it, you forgive them. And if they don't, in a different way, you forgive them, too.

8. You cease to believe in perfection in pretty much every area. There aren't any perfect people, perfect jobs or perfect lives. Instead, you pivot towards an appreciation of what is (to use the psychoanalyst Donald Winnicott's exemplary phrase) "good enough." You realise that many things in your life are at once quite frustrating – and yet, in many ways, eminently good enough.

9. You learn the virtues of being a little more pessimistic about how things will turn out – and as a result, emerge as a calmer, more patient and more forgiving soul. You lose some of your idealism and become a far less maddening person.

10. You learn to see that everyone's weaknesses of character are linked to counter-balancing strengths. Rather than isolating their weaknesses, you look at the whole picture: yes, someone is rather pedantic, but they're also beautifully precise and a rock at times of turmoil. Yes, someone is a bit messy, but at the same time brilliantly creative and very visionary. You realise – truly realise – that perfect people don't exist – and that every strength will be tagged to a weakness.

11. You fall in love a bit less easily. It's difficult, in a way. When you were less mature, you could develop a crush in an instant. Now, you're poignantly aware that everyone, however externally charming or accomplished, would be a bit of a pain from close up. You develop loyalty to what you already have.

12. You learn that you are – rather surprisingly – quite a difficult person to live with. You shed some of your earlier sentimentality towards yourself. You go into friendships and relationships offering others kindly warnings of how and when you might prove a challenge.

13. You learn to forgive yourself for your errors and foolishness. You realise the unfruitful self-absorption involved in simply flogging yourself for past misdeeds. You become more of a friend to yourself. Of course, you're an idiot, but you’re still a loveable one, as we all are.

14. You learn that part of what maturity involves is making peace with the stubbornly child-like bits of you that will always remain. You cease trying to be a grown-up at every occasion. You accept that we all have our regressive moments – and when the inner two-year-old you rears its head, you greet them generously and give them the attention they need.

15. You cease to put too much hope in grand plans for the kind of happiness you expect could last for years. You start to celebrate the little things that go well. You realise that satisfaction comes in increments of minutes. You're delighted if one day passes by without too much bother. You take a greater interest in flowers and in the evening sky. You develop a taste for small pleasures.

16. What people in general think of you ceases to be such a concern. You realise that the minds of others are muddled places and you don't try so hard to polish your image in everyone else’s eyes. What counts is that you and one or two others are OK with you being you. You give up on fame and start to rely on love.

17. You get better at hearing feedback. Rather than assuming that anyone who criticises you is either trying to humiliate you or is making a mistake, you accept that maybe it would be an idea to take a few things on board. You start to see that you can listen to a criticism and survive it – without having to put on your armour and deny that there was ever a problem.

18. You realise the extent to which you tend to live, day by day, in too great a proximity to certain of your problems and issues. You remember – more and more – that you need to get out and get a perspective on things that pain you. You take more walks in nature, you might get a pet (they don't fret like we do) and you appreciate the distant galaxies above us in the night sky.

19. You recognise how your distinctive past colours your response to events – and learn to compensate for the distortions that can result. You accept that, because of how your childhood went, you have a predisposition to exaggerate in certain areas. You become suspicious of your own first impulses around particular topics. You realise – sometimes – not to go with your first feelings.

20. When you start a friendship, you realise that other people don't principally want to know your good news, so much as gain an insight into what troubles and worries you, so that they can in turn feel less lonely with the pains of their own hearts. You become a better friend because you see that what friendship is really about is a sharing of vulnerability.