My mother has a similar personality. At 84, she still thinks she's worthless. Blames it on her mother's child-raising skills.

I know that the old saying "be yourself, everyone else is taken" may not be the right thing to say.

I agree with other posters who've suggested finding something that you're really good at. It will build your self-esteem. Don't ever think you've got to change to please everyone. Sometimes it's good to stand out from the crowd. I find forums can be a good way of establishing rapport whilst you build confidence to be yourself.

I'm a female plane spotter (passenger ones). I've met some really interesting people either online or near my local airport (in the UK). Whilst we haven't forged any lasting friendships or met again, there's a rapport which builds knowledge and confidence.