The daughter of one of our partners has just begun her first house job and her father is inevitably sharing her anxiety. Her induction period included an introductory lecture from a defence organisation which frightened the life out of her - all those things she had to remember to do, how perfect she had to be...

How different it was in her father's day, he reflected. His own introduction was more brutal. 'Welcome to medicine. During your career you will almost certainly kill several people. It's part of the job. Learn from your mistakes and get on with it.'

Short, sharp and to the point - but arguably more supportive. Of course doctors want to avoid making mistakes or missing esoteric diagnoses, but sooner or later we'll all do it. We can all think of patients who might have done better had we made different decisions. Unfortunately, hindsight has 20-20 vision - and all too easily leads to profound feelings of guilt.

Sadly, medicine (and especially primary care) has to cut corners - it is impossible to do anything else. If we investigated everyone obsessionally to exclude all possible diagnoses we'd see about five people a day. Ten-minute appointments would be a thing of the past, and telephone consultations would be completely off limits. Every febrile child would have a lumbar puncture, everyone with dizziness an MRI scan and everyone with dyspepsia a six-monthly oesophagoscopy. The cost of the NHS would rocket; each GP would only be able to deal with a list of about 300 people, so millions would be left without access to a doctor and therefore die of simple diseases like appendicitis.

The fact is, practising medicine perfectly is impossible. Therefore we shouldn't allow ourselves to be burdened with impossible expectations, because these bring a risk of inappropriate stress, depression and suicide. We also need to be supported when our necessary shortcuts turn out to be wrong.

For all doctors, the target should be 'doing our best', rather than 'being perfect'. It's an attitude that society, GPs and newly qualified house officers all need to adopt.

• Dr Lancelot is a GP from Lancashire.