After six months as a non-executive director, I have discovered the worst thing about the job. It isn't conforming to the endless, tedious minutiae of the combined code. That is dismal, but has to be done, writes Lucy Kellaway.

It's not posing for the annual boardroom photo, which is like playing a surreal game of Twister. "Put your left shoulder forward", demands the photographer. "Now turn your whole body to the right. Now hold your right elbow with your left hand, that's it, now can you look more relaxed? Okay, everyone, chat to each other naturally and try laughing?"

This was also bad, but (arguably) has to be done, too. No, the worst thing by a very, very long way was a compulsory visit to the neighbourhood bowling alley.

A couple of weeks ago, the entire board and senior management stood in clumpy, flat shoes and took turns at sticking two fingers and a thumb into a heavy ball and rolling it in a straight line to knock down some skittles. Throughout two long, shameful games my ball went into the gutter time after time.

Any warmth that this was meant to generate in terms of team bonding was submerged by a much more powerful feeling: failure. As I took my turn to throw the beastly thing, I felt a heat in my face that I have hardly felt since school days. This is the feeling that comes with being very bad at something, and I used to feel it all the time in sport, in drama, in art, in Latin and in spelling.

I described this episode to a friend, who looked sympathetic and said he had recently felt something similar. He had given his first after-dinner speech, which was intended to be comic but no one had laughed. He felt so bad afterwards he had to self-medicate with a tumbler of whisky and sleeping pills.

The great thing about getting older is that this sort of public failure gets rarer too. The feeling of being exposed as hopeless is so horrid that it sends a warning to the brain to avoid such activities in future.

It is only occasionally that life throws a nasty team-building activity at us, and the most rational response is: first, to develop strategies for avoiding that sort of thing in the future; second, to repair the damage done to the ego by reminding yourself of anything else that you are good at.

As I put this theory to the failed public speaker, he looked at me uncomprehendingly. For him, the only way of dissipating the shame of failure was to learn to succeed at that very thing. He said he had decided henceforth to accept every public speaking invitation that came his way until he had cracked it.

"That's mad," I said. "You don't like it, it's hard, you don't need the money, so why bother?" "It's because I can't bear being bad at things," he said. "Neither can I," I said. "That's why I don't do them."

Afterwards, I turned it over in my mind. My quitting strategy surely made me a coward and a weakling. His strategy made him not only a man with backbone, but a winner.

Later, I asked another successful friend which side she was on. She said she doesn't care if she is good at things: every year she learns a new skill, the latest being Italian. Life isn't a competition, she said, priggishly.

This double attack from two friends laid me low for a bit, but I now have the ideal weapon with which to fight back. I've been sent a proof copy of a delightfully slim new book by Seth Godin called The Dip - little book that teaches you when to quit (and when to stick).

Godin's theory is that quitting is a vital part of success. The worst thing any of us can do is to try to be well-rounded: he urges us to concentrate all efforts on the things we are going to win at, and quit everything else.

"A woodpecker can tap 20 times at a thousand trees and gets nowhere, or tap 20,000 times on one tree and get dinner," he says. It's a neat point that I'm going to e-mail to my friend and remind him that I'm tapping at my journalism tree and I suggest he goes on tapping at his legal one.

Godin's point is that we live in a highly-specialised economy where there are big rewards to people who are the best in their area and no rewards to those who aren't. He admiringly cites Jack Welch's famous strategy of only allowing GE to remain in markets in which it could be number one or two, and quit all the others.

Any mention of Jack Welch in a theory makes my heart sink a little, though I was still feeling smug overall until I read: "If you work at a big city newspaper . . . circulation is dropping . . . . Every day you stay is a bad strategic decision, because every day you get better at something that isn't useful - and you are another day behind others who are learning something more useful."

This wasn't very motivational for me, everything considered. Though actually he is not right about this. In fact, he's not right about any of it.

Firstly, life in a declining industry can be fine. It depends on the speed of the decline. Secondly, trying to be number one or number two is a bad strategy. If everyone tries this, then everyone apart from numbers one and two will fail.

In any case, not all of us are that bothered about being number one. In bowling, I would have been very happy to be number 15, so long as someone else was number 16.

As most careers are at best only medium-successful, the trick is not to make like a woodpecker. It is surely to be as rounded as possible.

So it may be perfectly sensible to take up after-dinner speaking and only be adequate at it, if that's what you want to do. It is also fine to spend evenings and weekends practising throwing heavy balls if that's what you want to do. Equally, it is fine to quit, if it isn't.