I still enjoy each day and despite the national scene - the carping criticisms, the often unreasonable demands and the silly distractions such as league tables - the good times still outnumber the bad.
But my complacency was slightly undermined when the local secretary of the National Association of Head Teachers asked me to write about my reasons for staying on. It prompted thoughts of an excuse note - or an epitaph! With so many heads rushing for the exit, I had the uneasy feeling that perhaps they knew something that I didn't.
I started in the same year that Margaret Thatcher came to power. I've outlasted her, even if she has influenced my life more dramatically than I have hers. Coping with rapid change has been the key-note of my career. Whenever there has been the remote chance of a boring routine being established, the national curriculum, local management of schools, special educational needs, OFSTED, primary league tables, a surge of pro-active governors, new school buildings and the fourth LEA reorganisation have kept me on my toes. And then there have been the local traumas: teacher redundancies, child abuse cases, deficit budgets.
I've seen more than 40 teachers come and go, enjoyed the company of six deputy heads, been entertained by the idiosyncrasies of five caretakers and gratefully accepted the guidance of four resourceful secretaries.
Probably the greatest joy of all has been watching hundreds of children growing through our school. Each has brought his or her own brand of humour, interest and irritation to my life; some continue to do so by bringing their own children to us now.
A cynical, prematurely-retired headteacher friend told me that there are old heads, there are effective heads but there are no old effective heads. I'm determined to prove him wrong. After all, if you can keep your head when all around are losing theirs, nowadays you are in a minority!
Bob Aston is a headteacher living in Rainham, Kent