You wouldn't say it to a friend
What the commentary costs you
The last several chapters took the beliefs one at a time. This one adds up the bill.
You're paying in mood and in mental health. Angus MacBeth and Andrew Gumley pooled twenty samples from fourteen studies that had measured both how kindly people treated themselves and their levels of depression, anxiety and stress. The association was large. The harder people were on themselves, the more symptoms they had. In Gilbert's study of fears of compassion, when everything measured was put into one analysis, self-criticism was the only significant predictor of depression. These are associations, measured at one point in time. Depression makes people self-critical, as well as the reverse, so the arrow runs both ways. But a habit that so reliably keeps company with depression isn't one to regard as harmless.
You're paying in progress. On the evidence of chapter 3, self-critical people get less far with their goals, across every area studied.
You're paying in what you don't attempt. This cost is the hardest to see, because it's made up of things that didn't happen. You didn't go for the promotion, and you never joined the choir. There was a course you didn't sign up for, because you'd be the worst in the class and you knew what you'd say to yourself about that. Someone who's savaged for every failure learns to stay where failure is unlikely, which means staying inside what she can already do. A life lived that way gets smaller over the years. From the outside it looks like modesty or caution.
You're paying in accuracy, as chapter 4 showed. Your picture of your own abilities is lower than the facts support. You're making decisions about what to apply for, what to charge and what to say in meetings on the basis of a biased report.
You're paying in the ability to enjoy what you do well. The commentary has plenty to say about failures and nothing about successes. When a piece of work goes well, it's silent, or it notes that anyone could have done it, or it points out the flaw. So your achievements don't register and the failures do, and after enough years your memory holds mostly failures.
You're paying in energy, for the reason in the last chapter.
And you're paying in sleep. The midnight review, with its agenda going back to 2016, is the commentary's longest performance of the day, and it comes at the hour when you're least able to answer back.
I should put the other side. You may feel that the commentary has driven you to achieve things, and you may have achieved a good deal. I'd say you achieved them because you care, you work hard and you have high standards, and that you did it in spite of carrying a heckler the whole way. The research in chapter 3 suggests you'd have got at least as far without one. I can't prove that about your particular life. But it's worth asking whether you'd wish this method on anyone you loved. If your son grew up to talk to himself the way you talk to yourself, I doubt you'd be pleased that he'd learned discipline.