As humans, we have walls we put up (consciously or otherwise) to keep people from getting into our personal lives and getting hurt and what not. Control over your relationships with other people and society in general increases once you realize those walls are there and you figure out how to manipulate them. Let's say, for just a moment, you devoted yourself to someone for whatever reason, fully and for a long time, and then they let you down in some way. That's the first time you should realize you're making walls. Shutting yourself out from the world in depression or sadness or angst; whatever the emotion is, you're creating walls. Most people just let the walls create themselves and live their lives from that point on letting their walls rule their life. It's at that point you should begin thinking about how to manipulate the walls, it makes things so much easier to be able to choose who you want to be friends with consciously. If you can decide who to put walls up against to block out, then you can essentially decide who influences you, who relationships of any sort will be with, and, thus, who you are.