Join a library, get out some really absorbing novels, curl up on the sofa with a massive cup of tea and read by lamplight. very good on rainy days.
Buy a bag of fresh coffee and brew yourself a cup every morning. heat milk in the microwave and use a small cafetiere to make barista frothed milk by half filling it with warm milk and pumping the lid up and down until the milk is thick and foamy. Costs about £2 a week for a massive latte or cappuccino every morning.
Try Treacle Moon or Waitrose own brand bubble baths for cheap but good scents - lime or clementine and giner for about £2 each.
Go for walks at dawn, sunset or the Golden Hour (late afternoon when the sun gets very rich and yellow. Walk slowly and literally stop to smell the roses, rub lavender between your fingertips, watch a caterpillar or beetle cross the road, listen to birdsong, stroke a cat. Spot wild hares, foxes, deer if you live in the countryside.
Track down some good yoga videos online (Adrienne is good) then take your mat (or if you don't have one a blanket or beach towel into the garden and do a twenty minute stretch.
Light a candle and find a good meditation track on youtube. (Jason Stevenson has a nice voice.)
Get a notebook and start journalling - you can make a bucket list or write a gratitude list or plan a holiday - something uplifting.
Look at seasonal bucketlists online. They often have inspiration for free or low cost things to do e.g. go blackberrying and make a crumble or plant bulbs for spring (bags of gorgeous daff bulbs in our local garden centre for £2.75)
On Spotify or Youtube have a memory lane session and play all your favourite songs and the hits from when you were a teenager, or the time in your life when you felt most carefree.
Have a pamper session. Facial steam, do your brows, manicure and pedicure, paint your nails, body brush and then massage with any body lotion or cream you have already.