How can I be confident if there's nothing to be confident about?

There's nothing good about me and I fail everything I try to do. I can't seem to improve. I have no skills, I'm not good to others, and I can't seem to change anything. I'm already too old to start building all the skills I need, there's no more time for me to take to improve. Plus, every time I try to improve I just fail, every single time. It'd make no sense for me to be confident when there's nothing good about me.
How can I be confident if there's nothing to be confident about?
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