Having your actions line up with your beliefs is one of the fundamentals of life. Since I was raised in a religion in which I could not believe, as hard as I tried to (at times), I felt a basic lack of this alignment, in that participation in the religion was forced. Yet I resisted. I told people openly that I did not believe in it, and I left it at 16 rather than accepting the next step of the "priesthood" that I was up for. I simply could not do it. A few years before, on a boy scout camping trip, we were all supposed to stand up and say how much we believed in it (a ritual called "bearing testimony") and I didn't. I was the last one after every other kid had done it, and I just sat there and didn't do it, until finally the leader gave up. It was hard because my cousin was on the trip too, and I didn't especially relish being the odd guy out. The kids who were not especially convinced yet talked about their testimony needing to be stronger, etc... I could have done that, I guess, but I was stubborn in that conviction that it was wrong to say you believed something that you didn't.
If you think believing in something that you don't is a matter of choice, then I recommend that you take something you don't believe and will yourself to believe it. Once you've succeeded in doing that, come back to me and we'll talk. Of course one method of doing this is to stand up and lie and get people's approval until it starts to feel good. Maybe eventually then you will actually be convinced.
I write about this as something that for me is a positive, but that you could turn around and see as negative. Stubborn, anti-social, too convinced of my own positions, etc... I go back to that 14-year old kid and I wouldn't tell him to do anything different. I still think that what I did was correct.