Just try not to snap at everyone who tries to get close to you. Someone will come along who has either the patience or charm to lower your walls (: I wouldn't worry too much, there'll be someone. Your friends will know that you aren't massively open, and thats perfectly fine!! Not everybody feels the need to share every second of their life with everyone! Choosing the right person to open up is advisable, just choose someone who will listen and actually respond so you feel as though they have let their walls down as well :) Its a two way street! And it takes time to open up, after you've tried it with a few people it will become easier.
Don't think about this as a problem. Some people don't feel comfortable talking about their lives and that's fine, it won't make you feel better if you force yourself to speak to someone. It can even make you feel worse if you're not ready, because it can make you nervous. Don't worry, the right person will come, someone who is worth your time and trust, someone who'll listen when you are ready to talk and who'll respect you when you're not. Anyway, you should find out why is it so difficult for you to open up. It can be because you don't trust people, maybe you're afraid they won't keep your secrets, maybe you think they'll judge you and look at you differently, or maybe you think people don't really care and they're just curious. There are many other reasons, and before you learn to talk to someone you should first try to understand what's keeping you from doing it. Just remember, it's better to have 1 or 2 friends who are there for you, and to really let go and tell them everything, than to force yourself to speak because you're afraid you'll lose someone. If they care, they won't give up when you first push them away.
well its a tough question. people have trouble opening up to others for different reasons. Sometimes its fear of them being unable to handle your feelings. sometimes its generalized lack of trust. The list goes on, in truth i would say that the most important question to ask is why you are building these walls, once you know that it will be easier to know if your lack of trust is reasonable or not. Generaly (from my experience) the first step is self awareness, it is possible to build walls to hide things from oneself, or it could be that you have been hurt by somebody else and are afraid of it happening again. All in all it sounds like you might be putting a lot of pressure on yourself. Try to relax a bit, sometimes a bit of time is what is needed most. It seems that you have the desire grow and that alone is something to be proud of.
Opening up is a really hard one for me. Recently I've made a lot of great strides in doing it, but, it's still a challenge. If we're not careful, we allow our defenses to become more like dams, and then nothing gets out. So if we open up and express our vulnerability, then it all comes spilling out. That's what it was like for me. I hadn't cried in years, and when something finally hit me, that dam broke and it was insanely hard to stop crying. But as I've searched more about myself, and searched more of what the scholars say about vulnerability, I'm realizing that it's a happy medium. You need to know HOW to be vulnerable, but you also need to know WHEN. And there's lots of factors that help you determine when it's safe to do so. I recommend you explore deeply what your vulnerabilities are with yourself first, and then learn to share them. There's many different reasons as to why we DON'T share them in the first place, but the idea that this vulnerability we're experiencing is for us alone is common, therefore judgements and fears abound, but, that's not the case.For more about vulnerability, this video might help you. The speaker is also a researcher who's written some great stuff on the subject: https://www.youtube.com/watch?v=iCvmsMzlF7o