Three teachers made me the person I am today. The first was Howard Robinson, who taught me biology from 13 to 18 at Framlingham college, Suffolk. He was also my house tutor.
Howard was a very exuberant, slightly mad character who did things I always remembered because they were so eccentric. For example, he would explain how the body transports oxygen by running round the classroom pretending to be a haemoglobin molecule. He'd pick up a beaker of water and pretend it was oxygen and throw the water all over us to show us how oxygen dissociates from the blood.
He was so full of life, so manic, waving his arms around like a windmill and running up and down the classroom, we gave him the nickname Zowie. He was a very sprightly man, slim with black hair and glasses who looked a lot younger than he was. He didn't turn me on to biology; I was already a bit of a biology freak, but he made me more aware of the subject. From the age of four or five I knew I wanted to be a doctor - or if that didn't work out, a turnip farmer!
Howard also taught me a very important lesson - you only really learn if you're having fun. That's something I've tried to emulate. If I'm discussing topics such as teenage sex or smoking, or whatever, on television, I try to make them fun so young people learn as a by-product of having a good time.
I call him Howard now, but at school he was always Mr Robinson, even when I became head of the day boys. It was only when I went back as an old boy to give prizes and got to know him better that I started calling him by his first name. We both enjoyed singing and drama. I was in the church choir, and he did a lot of singing and acting.
At the same school there was a guy called Tony Lawrence who was an English teacher, and he inspired me in terms of drama. I was quite shy and retiring at school but under him I appeared in Midsummer Night's Dream and loads of musicals such as Oliver!, Jesus Christ Superstar and West Side Story. I loved everything to do with showbusiness and had an enormous interest in the theatre. Mr Lawrence organised school trips. We never went to London, but we saw a lot of shows in East Anglia. It was through Tony Lawrence that I learned about Harold Pinter.
The other person who inspired me was a doctor who taught me at St Mary's Hospital medical school in London. I would describe Dr Richard Lancaster as one of the last great physicians. He was a true gentleman in every sense of the word. He was charming and polite and treated every patient as though they were a member of his family. Nothing was too much trouble. He was slim and athletic and looked exactly like Roger Moore did in his heyday. He wore a bow tie and spoke terribly well. He was also a great physician. He taught me humility and a lot about how to relate to people - things you could never learn from a textbook.
I have kept in contact with all three men. I saw Howard Robinson and Tony Lawrence fairly recently and am in touch with Richard Lancaster. They are all on my Christmas card list.
David Bull, 30, is a part-time doctor and presenter on the BBC1 programme Watchdog. He leads a drugs roadshow with the teen band Orange Orange and writes for the girls' magazine Shout. He was talking to Pamela Coleman.
THE STORY SO FAR
1993 Qualifies as a doctor
1993 Becomes houseman at St Mary's Hospital, Paddington
1995 Makes first television appearance (as a doctor on Sky Travel)
1996 First BBC appearance on Newsround
1998 First book, Cool and Celibate?, published (Element Books pound;3.99)
September 1999 Second book on teenage health, What Every Girl Should Know,
published (Element Books pound;4.99). Makes debut as Watchdog presenter on