I used to hate UK winters and feel really down at the prospect of it being months until Spring. Then I decided I didn't want to waste my life feeling miserable for a quarter to a third of the year! So much of it is about mindset and leaning into Winter since you can't change the seasons.
So now I do all of the hygge things that Mumsnet seems to hate. Candles, lamps for low lighting, fairy lights indoors, blankets, warm bedding, hot chocolate. The whole cliche of getting cosy. But it helps if my house feels comfortable and somewhere to relax in.
Spend some money to get the right stuff. A really warm winter coat, a hat and gloves that you love. Knitwear that you enjoy wearing. I agree with a PP about bright colours....my Winter coat is hot pink and makes me smile.
I wrap up warm and go on walks during the daytime. I go to the gym or do yoga at home when it's dark.
I focus on comfort food. Casseroles with lots of vegetables, spicy soups, food that feels hearty. I also take my vitamins.
I find really good books, TV series and podcasts. I go to bed earlier and rest more. I view it a bit like I'm hibernating like the rest of nature does.
Find things to look forward to. Book a holiday, plan things for Christmas, plant bulbs for the spring, go to a bonfire night display. Go out and socialise with friends.
In Spring and Summer I focus on the garden and making that nice, we have BBQs and I sit outside with a gin and tonic. In the colder months I focus on the house and making that feel lovely. Get decluttering, we go for pub lunches, go to the cinema with friends, I drink red wine and treat myself to trying a different bottle with DH each weekend.