One of the most common observations in psychotherapy of people with depression or anxiety is that they hold themselves to impossibly high standards, although they have a perfectly sensible evaluation of everyone else. Their own failures are catastrophic; other people’s are minor setbacks. Other people’s successes are well-deserved triumphs; their own are never good enough, flukes, they don’t count.
The first step in challenging these unhelpful patterns of thought is to simply point out the double-standard: why are you such a perfectionist about yourself, when you’re not when it comes to other people? The idea being to help people to think about themselves in more like healthy way they already think about others. Turn the map of yourself upside down - what do you actually see?