Gonna tack on here with a Protip: never make a trip with empty hands. If you’re going for a whazz, take some of the rubbish with you, or take the cups and plates out to wash them. If you’re the type to think “I’ll do that later” then it’ll only ever get worse. It’s far easier to do little things when you can, than it is to let it get so bad you have to call a specialist.

If you’re a smoker that’s hellbent on smoking indoors, buy an ozone generating air purifier and replace the filters regularly. (Wear gloves because you’ll be touching the same tar that’s in your lungs. If you’re lucky it’ll disgust you enough to quit)

If you put a bin next to the desk then make sure it has bin bags, if you’re a canned drink person then crush the empties and tear up the cardboard so you can put it in the recycling (It’s satisfying as hell to go primal on some card when you’re tearing it up)

It sounds like a lot of effort, but believe me when I say that I’ve seen what it looks like when someone lets their room become like this, and it involves having to remove all the carpet, strip the paint off the walls and bleaching the floorboards to try and kill off the rot (along with a course of antibiotics to stop the rot from killing them.)