Daily SPF for your face and neck and décolletage if going outdoors. I use La Roche Posay Hydraphase UV Intense Légère SPF 20 all year round, and their Anthelios XL SPF50 ultra-light fluid in the summer/on holiday. And hide from the sun with hats, shade etc.
Nice baths with nice bath things. Candles, nice aromatherapy bubbles or oils etc. Feels very luxe and decadent.
Second the daily walk. Clear your head, get some fresh air, increase your stamina and fitness. It cheers me up no end, even when I’m convinced it won’t.
A good, smart, winter coat that you love and goes with everything. Mine came second hand from a charity shop 20 years ago and I still love it to death and feel great in it.
Get yourself something stupidly soft to snuggle in. Cashmere/soft merino/silk scarf, cardigan, jumper, pyjamas, gloves, whatever. Super soft always feels expensive and delicious and like being spoiled to me. And I find cheaper cashmere (uniqlo, H&M) wears better/bobbles less.