I am a positive person. I was raised to be a positive person thanks to my mother. But... She forced positive emotion even when it was negatively impacting her.
I was trained in school to search outside of the box no matter how outlandish it may seem. I decided in adulthood that positive is sometimes negative.
Because of the above conclusion, I define positivity potentially differently than others would. I look at impact as opposed to things like happy or sad. Sometimes sadness can have a positive impact. So, if it is adding value I see it as positive. If it detracts from my day, it is negative. Manic euphoria would be an example of a positive emotional state with a negative impact. I try to avoid that one. Neutrality can have a positive or negative net impact. Its all about where you've come from, where you are and where you need to go.
My ability to maintain a positive net result each day is pretty solid. I rarely sway because if one aspect is negative I try to balance it in other ways. Major life events or episodes are pretty much the only things that take me into a negative impact oriented state. Even then, I rebound pretty quickly.
It is all about balance. Sometimes negative feelings will come. Negative defeatist thoughts occur. Poor eating days happen. Sometimes I'm spiritually focused on the self and not the whole. That's ok. The goal for me is to recognize it, accept it, allow it to be as long as it needs to and then work to shift it or balance it with another aspect so that I do not get lost in the imbalance.
I'm not aiming for pure rainbows, sunshine and unicorns. Just a nice flow of smiles and overall happiness.