The dumbest childhood vow I ever made was to finish every book I started. Maintained well into adulthood, this policy turned reading the first page of any volume into a miniature death sentence. I imagined my compulsive completion a sign of adult seriousness. In truth, it was a vanity – a poorly thought-out and typically adolescent caprice.

As a consequence of this inane commitment, I reserve a special loathing for a host of books that I shouldn't have been reading in the first place. I remember working as a summer camp councillor in my 20s and absolutely despising poor Russell Banks' Book of Jamaica, yet never allowing myself to read something else because I had already started it. I say "poor" Russell Banks, because I love his other books, and the fact that I forced myself to keep reading a book for which I was not remotely in the mood was not his fault.

I have occasionally heard from a reader fuming because he or she did not enjoy one of my novels yet still read to its bitter end. I reject this fury out of hand. For pity's sake, if you don't take a shine to a novel, there are loads more in the world; read something else. Continue suffering and it's not the author's fault. It's yours.

Granted, it's a good idea to give some books a chance even if they don't grab you at first, especially if they come recommended by someone you trust. But 50 pages is plenty, and with some books I have an allergic reaction after two or three.

Reading time is precious. Don't waste it. Reading bad books, or books that are wrong for a certain time in your life, can dangerously turn you off the activity altogether. The sign that I don't like the book I'm reading is finding myself watching reruns of Come Dine With Me.

Big Brother by Lionel Shriver is published by HarperCollins, £6.39 from guardianbookshop.co.uk