Clean The House
Your family or housemates will appreciate this one…! Tidying everything up can leave you with a really satisfied feeling afterwards, and the process of tidying up can be a distraction from the urge to self-harm (if there’s loads to clean up then it can be a big distraction). By having your surroundings all neat and organised, you might find your thoughts become more organised, and easier to control.
It’s important to find what works for you. If this doesn’t help, don’t worry. There are plenty of other ways to cope. See other ideas of things to try.