Umbrella

I read in Elaines's workbook about using the idea of an umbrella to protect yourself from the moods of strangers when you are out. I have been doing something similar with what I called my bubble, but the book said to try to picture an umbrella. As an HSP I am a receiver of other's feeling, moods and tones and this leads to processing deeply the information around me. 

Then the umbrella is down it can collect all the emotions that others are giving off.  But if you open the umbrella it can bounce those emotions back to them and not be affected by them. You are broadcasting that you are not receiving their moods but saying to them, "Hello, I am busy and doing my thing."

You think about the umbrella up and your mind is thinking about what you need to do so that you are not receiving but sending out that you are busy. I have done this a number of times, with my bubble, but I am also seen as not friendly. Sometimes I have missed seeing people that I know, not acknowledging them. I do not have a smile on my face and they see me as unhappy. This has happened at work. I am in such deep thought, trying to get things done, that people think I am not liking what I am told or asked to do, completely miss reading my attitude.  So here is a question, how do you protect yourself and seam friendly at the same time? We all see through fake smiles.