I packed a tennis ball in my carry-on – it changed how I fly

Does packing a tennis ball in your carry-on actually help on long flights? Let’s find out (Picture: Maria Astardjieva)

Around the five-hour mark of my long-haul flight from London to San Francisco, everything hurts.

My lower back is throbbing, my leg muscles are stiff, and I’ve exhausted every possible sitting position, none of which are comfortable enough for longer than a minute.

Stuck in the window seat, with my neighbour fast asleep before the safety demo had finished, I bide my time before the inevitable ‘excuse me, can I just squeeze past?’.

But then I remember: along w...