Little things that can make you feel better when you feel terrible and don’t feel able to do anything:
Being clean. If you can manage to have a shower, that’s great (even if you just lie on your bed in a towel after and don’t get dry). But if you can’t, you could try just standing under the hot water of a shower for a little while, or rinsing your face with warm water, swilling some mouthwash, putting dry shampoo in your hair, wiping your face and underarms with a wet wipe, putting on some deodorant, changing your socks or t-shirt or underwear, etc.
Look after your body. Drink a glass of water. Make sure you’ve taken your medication if you take any. Have you eaten anything in the last four hours? Try eating something - you don’t have to spend a long time making it. A piece of toast, some cereal, some fruit, a cereal bar, the components of a sandwich even if you can’t put them together.
Sunlight. If you can, try going outside (even if you just go for a minute in your pajamas and slippers, just outside the door). Close your eyes and tilt your head up to the sky. Take a few slow, deep breaths of fresh air. If you can’t do that, make sure your curtains are open, and try sitting by the window for a few minutes. Maybe open a window to let some fresh air in.
Look after your environment. Being in a dirty environment can often make you feel worse, and cleaning feels productive and you can admire your work at the end of it. Even if that’s just doing something small, like putting dirty laundry in the hamper, or putting trash in the bin, brushing the crumbs or loose hair off your sheets if you can’t change them, spraying air freshener or lighting a scented candle. Opening a window to let the air circulate. Straightening some cushions, or shoving a few things that are out of place in a drawer so they aren’t in sight.
Do something self-soothing. Watch your favourite episode of your favourite show, or listen to your favourite album. Drink a cup of tea. Put some nice-smelling lotion on your skin. Wrap yourself up in a soft blanket. Find a picture of something cute or funny and send it to your friend. If you live with someone else, sit in the same room with them, or give them a hug. If you have pets, play with them or pet them or give them treats. Read a poem or a few pages of a book. Watch your favourite youtuber’s new videos. Scroll down your favourite blog. Put on some of your favourite perfume. Do something to do with your hobby. Play a video game or mobile phone game. Look through old photographs. Doodle something on the back of a piece of paper. Read a positive news article. Trim or paint your nails. Put on your favourite t-shirt or set of pajamas. Read a random wikipedia page (maybe about your favourite animal or celebrity or a historical event). Send someone a kind anonymous ask.
Most importantly: congratulate yourself for doing those things. Sometimes the tiniest things can be really hard, but doing them can make you feel better. Even if they seem like such small things, it’s important to recognise that you did something good by doing them. Be proud of yourself.