Always remember that perception IS the reality. So even if you feel bad, psych yourself into feeling good.
I had a lousy day today...lots of pressure at work, last night sucked for a series of reasons, it was hot muggy and raining outside today (= yukky in my book), and I was trying to find my boss so I could submit my resignation today (after 6.5 years). Couldn't track him down. More stress.
I was meeting a woman for coffee after work and I really didn't want her to see me in a fvcked up mood. I literally had to talk myself into a good mood.
I read a post last night about someone being scared to approach chics in a bar or something. One of the responses was to "step outside of your body" and view the approach in the third person. This is good advice and always works. I teach graduate school and sometimes you just have to disassociate yourself. It only takes a couple of minutes before you are naturally in the flow of whatever situation you find yourself in.
I greeted her this afternoon with an enthusiastic "Hey! blahblah" How's work? Do you finally have a project to work on? Blahblah" feigning genuine interest (there was some, because I knew it was important to HER). The first couple of minutes in the cafe, she and I ordered our coffees and shyt, and then fell right into 1.5 hrs of good discussion (that means more than light "convo"). I completely lost my moodiness. Once alone again later, some of the lingering effects returned but much easier to brush off, after a long distraction with pleasant

company.
So, what is more important? It's not a black and white answer. Just remeber that you will always project how you feel. The key is to CONTROL how you feel.