You gotta start treating these thoughts for what they are; They're a symptom, just like intrusive thoughts where your brain decides to display the worst it can do.
They are not the be-all and end-all of your existence, absolutely nothing to do with your character or who you are as a person. Learning to take those thoughts and analyse them so you can work out the root cause is a skill that takes practice, but it's a skill that's worth putting the effort into.
A lot of depressive episodes are brought on by external conditions, so ask yourself these things when you feel yourself spiralling into a cycle of self deprecation and self loathing.
Have I drunk enough water today? Not just soda, coffee or energy drinks (they're absolute anxiety in a can, coming from a hard caffeine addict)
Have I eaten a meal today? Not just snacks or a small bite but a substantial meal that gives you nutrients.
How much sleep am I running on? The age old "don't listen to thoughts about yourself past 9pm" is a game changer.
"Have I spent any time outside / How much of my time has been spent on the internet/in front of a screen?" I don't want to sound like a typical internet denizen like I'm telling you to 'touch grass' from the ignorant place of 'the other side of a social media site', but there's a lot to be said for getting yourself somewhere natural and spending some time offline. Take a flask of warm drink, wrap up warm, find a park bench to sit on and just BE.
We're all just chimps with shoes and anxiety after all, gotta make sure we spend time outside else we start getting cabin fever.
Having a clean environment helps reduce that, I know the concept of cleaning while depressed sounds like torture but one of the reasons why our brains start lashing out at ourselves is spending too much time in a messy environment.
And one of the most important ones;
"What purpose do these thoughts serve?" If they don't actually benefit you in any way, then treat them as they are; the incoherent ramblings of a bowl of meat jelly that has electricity running through it.
