If I have not quite been myself for the last year, it’s time I explained why. I have spent the past 12 months lost in other people’s imaginations, the breadth and scope of which have been a revelation. This time last year, I became a judge on the 2019 Booker prize, whose winner will be announced on 14 October. I said yes instantly, in delight, knowing I would work out how on earth to fit in so much reading later.

Over the past 10 months I have been sleeping less, answering my phone little, not mentally present in queues or on public transport, and roaming instead the mountains of Kashmir, the villages of the Cotswolds, colonial-era Zambia and superhuman communities in Northern Ireland. I have found myself decrypting Shakespearean time travel and complicated sibling love in Lagos.

On the Eurostar to Paris during the Easter holidays, I was so absorbed in a novel that I stopped concentrating on the two overly excited children in my care

I ended up reading 151 books in six months. The dizziness of this experience was compounded by the extent to which I was travelling in real life. Stephen King once said that books are a uniquely portable form of magic, but – determined to read the old-fashioned way – I found myself lugging a heavy load of them around. Filming in Brazil, Senegal and Jamaica, for example, I checked in extra suitcases full of books, unwilling to put any limits on how many I might get through on each journey. The reality is that we had to read fast – very fast. If I were disciplined, it worked out at a book a day. If I were not, and lavished two or three days on a single novel, sleepless nights would ensue as I desperately raced to catch up.

I rarely had time to screen which books I would take with me, resulting in some eery coincidences. On a trip to see the Ark of the Covenant in Ethiopia, I found myself reading a story about it. It might have been the narrative themes of destiny and divine intervention, or the anti-malaria medication I was taking, but the book gave me a strange and unshakable chill.

On the Eurostar to Paris during the Easter holidays, I was so absorbed that I had stopped concentrating on the two overexcited children in my care – by now giggling too loudly at an iPad movie – prompting a French person in the seat opposite to say, “I don’t know what you people do at home, but this is the Eurostar.” The book I was reading had unpleasant notes of racism, too, with its pointed stereotype of a murderous African viewed through the gaze of a white man.

I have tended so much towards non-fiction in my adult life, because of the journalism and writing I do, but reading for the Booker was a study in the power of fiction to shape our social and political discourse. Haruki Murakami once said that if you only read the books that everyone else is reading, you can only think what everyone else is thinking. What I found is that if you only read the kind of novel you have always read, you can only think the kind of things you usually think.

The greatest insights I experienced during this period came from books I would never have chosen. I found new things to love in the most unexpected places: an English schoolboy who didn’t fit in; a couple of Irish gangsters scouring a Spanish port; a Vietnamese mother and son making sense of life in the US; the minute details of the life of a Swiss orphan who went on to become Madame Tussaud.

I realised that, like so many of us, I filter my book choices to reflect the world I already know. Reading stories that I would never have chosen, mistakenly believing them to be uninteresting or too remote from my concerns, reading them intensely, fast, sacrificing social and family commitments to make sure I gave them the time that they deserved: this slowly began to change me.

It wasn’t all easy. This process also turned out to be an exercise in overcoming my own deep sense of impostor syndrome – a belief that I was not qualified, literary or clever enough to be a judge on this prestigious prize. I found myself sneaking reading time in the corner of gaudy, harshly lit TV studios, when I imagined my fellow judges in beautiful, book-lined rooms, seated by a large window in quiet contemplation. At times, I thought about pulling out.

I was wrong, though. My fellow judges were the best thing about reading the Booker list – having to get through this much, this fast, is a good recipe not just for sleep deprivation, but also friendship. Now I totally get book clubs. I wouldn’t realistically advocate trying to read 151 books back to back, but if you would like to try our longlist of 13, you too can totally join this one.

• Afua Hirsch is a Guardian columnist