When I think about my happiest memories, they usually have a lot in common: it’s warm, the sun is soaking into my skin, and I’m probably in a large body of water. Sometimes it’s the turquoise river in Ardèche or I’m floating on my back in the sea on an unusually warm day in Hastings. I feel calm, safe and refreshed. My most joyful memories never seem to be in the cold or dark. Weirdly, even though I’m used to the flux of seasons we experience in the northern hemisphere, I can’t help but be shocked every time the clocks go back, leaves tumble from the deciduous trees and we experience the collective onset of winter blues. I can feel myself becoming sluggish, flat and struggling to rip myself from the sofa. As the colder months draw in, moo...