I Have Low Self Esteem

I hate that this is how I feel about myself! I let stupid childhood memories haunt me and just feel really undesirable most of the time so I just choose to sit on the sidelines and watch the rest of the world move on and have exciting things happen to them while I just wait for something to come along because I don't have enough security in myself to go for it! I hate how easy it to tear myself down! I crave validation from others but never receive it and it hurts but I'm honestly trying to change that about myself because it is really unbecoming and will become worse if I don't fix it myself.