Most? I doubt that very much. Most of us need to employ a range of techniques to try to manage our BP. If all it took was choice, we'd choose not to have it at all. I'm not saying positive thinking has no place, just saying that in an episode when BP is owning our azz, it just plain doesn't work. We can't simply "happy think" our way out of it. Doesn't work that way. (If that does work for someone, they probably ought to be re-assessed, because it's doubtful it's actually BP they're dealing with.)

Like being less pregnant?

While I concede there is a degree of spectrum within BP, there is a point where it isn't. Symptoms have to cause impairment -- have a negative impact on one's functioning in order to be properly dx'd. No such thing as "a little bipolar". (Disclaimer-- I realize you did not use that particular little gem, but it's hand in hand with it.)

Sorry to kind of jump on your case, but most of us have been told "just choose happy" a zillion times from well-meaning, but ill-informed people. So it hits a nerve. I beat myself up for DECADES attempting to reason my way out of it. It was my FERVENT wish to be able to do this. And it very much did.not.work.