The novelist and diarist refused to hope, until she saw how much her sister gained from it, regardless of the outcome

How to be hopeful: Nina Stibbe on why optimism is a gift – even if all your plans fall through

I used to think mild pessimism a reasonable byproduct of a riches-to-rags childhood and that never allowing myself to feel hopeful was entirely rational. I’d trained myself to expect the worst and not even to think about the best. It started out as self-preservation, but morphed into something to do with manners – being modest and deserving. Finally, it became a sort of superstition – like not stepping on the cracks in the pavement, or shoplifting when pregnant.

This changed suddenly some years ago. My sister Vic had a possible Big New Thing on the horizon. A huge thing that, if it came off, would change her life – in a good way. She had done all she could do, it was out of her hands now. She just had to cross her fingers and wait.

To my consternation, she seemed openly optimistic about it. She had it all planned and dragged me into it, telling me: ‘If this happens then this, and this, and maybe even this.’ She wrote notes about it on future dates in her Filofax diary, in pen, which I could only see as tempting fate or provoking the gods of destiny and fortune. Eventually, in desperation and for her own good, I told her to stop counting her chickens before they’d hatched.

My worry wasn’t only that she might end up disappointed but that hope itself – being greedy and presumptuous – was wrong and bad and punishable and might therefore count against her in some supernatural reckoning.

“Put it out of your mind,” I said.

“No, I want to think about it, I like the hoping,” she said.

“What if your hopes are dashed, won’t you be devastated?”

“Yes,” she said, “but at least I’ll have enjoyed hoping.”

I learned that day to allow myself to hope, and I have hoped for good and great things ever since. Some have happened and some haven’t, but the hope itself has been life-enhancing.

And it strikes me this is a much better way of going about things. That if a thing is worth having, it’s worth hoping for, and that the brief joy of hope is sometimes all you’re ever going to get. Also, no metaphorical chicken was ever scared away by someone counting it.

• Nina Stibbe’s Reasons to be Cheerful won the 2019 Bollinger Everyman Wodehouse prize for comic fiction. It is published by Viking (£12.99). To order a copy go to guardianbookshop.com. Free UK p&p over £15