Every time I am faced with a headteacher who is clearly failing, I always ask myself that question. Very rarely in my experience have I come across wicked people whose sins have found them out. No, the greater tragedy is to see talented, effective, witty people fall apart as the demands of leadership overwhelm them.
I would love to be able to say that I can spot the likely failures from the beginning but I cannot. That is even more disconcerting when you see colleagues that you had always assumed to be effective leave headships with their confidence shattered and their lives in turmoil.
Perhaps the best I can offer are some ideas on how to keep management's grim reaper from the door. A good starting point is to check out how you are doing with other people. Many heads who fail have lost the capacity for self-awareness. They are often devastated by teachers' and parents' criticisms.
It is a cliche that headship is a lonely business but you do need sounding boards, both inside and outside the school. In my experience, failing heads have become isolated and lonely well in advance of their departure.
Do not judge your contribution to the school simply in terms of the amount of time and effort you put in. Rarely do heads fail because they are lazy. A head in difficulty is often a head who burns the candle at both ends and loses a sense of perspective. If you are working more and achieving less, then you need to re-evaluate your work.
It can appear a bit anally etentive if you always make lists just to tick them off. However, setting management tasks each dayweektermyear allows you to say enough and no more. You will also gain immense satisfaction in reminding yourself of your achievements.
Accentuate the positive. I often get worried when I hear a headteacher incessantly complaining about the pupils, or the parents or the education authority or the world in general. You can talk yourself into a hole.
Check yourself if all you ever seem to do is complain. It will poison the atmosphere in your school and an unhappy, moaning head will often find their attitude reflected in the pupils and staff.
Perhaps more importantly, do remember that what you say is what you will become.
And, of course, you need to accept change. Many weary heads just cannot manage yet another round of changes. Yet, it is a fact of life. You are more likely to stay in control if you make change your servant and do not become its slave.
A good tonic is never to stop being amazed at what pupils and teachers achieve every day. Force yourself to ask at least one youngster every day what they have learned. You will be amazed and it will keep you in touch with the real life of schools.
One final point: recognise your limits. It need not always be onward and upward. We all know people who did an effective job at one level and felt compelled to go for the next promotion. If you move from reading this to the back of The TES to look for a new job, be true to yourself. It might just be that you would be happier and more effective if you stay where you are for now.
David Bell, director of education at Newcastle city council since 1990, started as chief executive of Bedfordshire County Council this month