Underselling

Someone recently told me that I undersell myself. I stammered with a million denials because its not part of my nature to believe that I might actually be worth something. I'm supposed to believe that I have a lot to offer as friend, partner, family member, citizen, etc. I can tell you what's wrong with me all day long, but don't ask me to tell you what's great about me or my life. So how can I wake up tomorrow believing the best about myself, that I'm really worth loving? I know that I can be funny and that I'm really smart but thats about it. I've been trained to think that I'm not good enough. I'm terrified of dating because I fear that no one will want me or that someone will be quick to tell him what a big mistake he is making. I don't feel valued and I don't feel worth much. I know that not feeling valued comes a lot from my own perceptions of what people think of me. That's part of the reason I'm so non-confrontational. I don't fight because I know they can come back with a lot of bad things to say about me. I also have to remember that very few people get told how great they are. I also know that I have to find some way to not care so much about what other people think about me. I just don't know how to turn that off. I know so many people who honestly don't care what other people think about them. They are open to advice and aren't closed off but if someone doesn't like them or what they are doing, they just don't care. I spend so much time editing my words and my actions to make sure no one disapproves or is unhappy with me. It's actually quite exhausting. Hmmm, I guess I hadn't really thought about that enough. If no one is trying at all to make me happy or comfortable, why do I work so hard to make them comfortable. Knowing that my family loves me doesn't mean I have to make sure I'm worth their love all the time. Go away inner monologue. It's time to change my thoughts and my perceptions. Ummm.... can anyone tell me how to do that?