I don't know how to be...........acceptable in public?

The job I had previously required me to interact with people frequently and it was draining. Now I am trying for a job that involves minimal interaction but one cannot avoid co workers and superiors. Here is the thing though: I was always polite and professional but,somehow, that doesn't seem to be enough. My former boss told me I appear aloof and that I need to open up and be more enthusiastic and I tried doing that but it felt like I was forcing myself or putting on a performance.

Even back in school, it always felt like there was an invisible wall preventing me from interacting with others 'properly'. I wanted friends and I was told I need to try harder and so I did. I tried a lot to be what people would like but that my attempts brought me only tolerance and not friendship. So, I decided to keep to myself and my activities, got used to sharing my thoughts and hyperfixations on platforms like tumblr and reddit and got to engage with people who with similar interests which I find to be more convenient.

At present, I do not expect people to read my mind and become best pals with me. Infact I perfectly understand why many wouldn't enjoy my company because I can appear rather dull and boring and I do not begrudge them for it. All I am aiming for is mutual respect and a healthy workplace free of misunderstandings. Right now, being at home has made me too comfortable for my own good but sooner or later, I have to go back to work. I need to work. But I am also terrified at the thought of stepping into a place filled with people and not knowing how to behave in the exactly right manner and messing up, as a result of that. How do I make it clear that I have got nothing against anyone? Somehow, politeness doesn't seem to be adequate and my brand of friendliness ends up being slightly overwhelming for the uninitiated.