The first step towards changing the way you treat yourself is to notice when you are being unkind or self-critical. It may be that your inner critic has been active for so long it does not register for you as being harsh, judgmental, or mean.
What are the go-to things you say to yourself when you don't succeed at something?
What do you say to yourself when you make a mistake or forget something?
Does that voice remind you of anyone in your past who was critical of you?
Reframing our critical inner voice takes awareness first and then compassion.