I do not remember where I got this from, but the last 30 years of my career this was hanging on the wall of my work space and it now resides on my refrigerator at home:
If you think of yourself as capable, enthusiastic and committed, you will act with confidence and determination.
If you don’t, you won’t.
There’s no truth about who you are.
There is no preordained way you must think of yourself.
You are not born with beliefs; you acquire them.
You have the power to redefine your identity anyway you want.
So, substitute positive characteristics for negative ones, and start living those from now on.