maybe working on something simple - I know this sounds stupid

but making a list of your insecurities first. why do you feel so insecure?

Then answer them.

lets say youre insecure because you think no one will like you

make up a phrase that combats it. Like, if I be myself I will find people who like me.

Say it like 10 times or more a day.

Know it sounds silly , see if it helps