I don't think most people are ambivalent and I'd still say a large majority of people likely make the choice to try and move past.
I know you've already gone into more depth on this,
@Air - but just had two cents to share.
I think making the choice to 'move past' tacitly implies a decision to start a process - any kind of process - towards resolving the problem.
Deciding to move past PTSD by denying it, for example, isn't moving past - it's denying. Deciding to accept that you are doomed to a living hell of symptoms isn't moving past, it's wallowing.
Even if the decision consists of: 'I need to address this properly but am overwhelmed by where to start'; that's a good step on the right road. Then, the person takes the next step, and the next.
To me, it's a fallacy to think that deciding to remain stagnant or in pain is actually a decision to move past something. It's more along the lines of accepting the negative.
I agree, it's also not altogether as easy as flipping a switch and poof, you are better.
But: most mental health treatments are based in flipping that same switch repeatedly, sometimes many times in a day. Every time I decide to challenge my own thinking - I'm actually making a choice to move past my old thinking. It's tiny, it's not like some major thing that fixes everything - but it does help me get better for the next 5,10,15 minutes of my life.
If we can understand 'moving past it' not as a one-time event, but as a daily, hourly choice to apply small, reasonable measures - then yeah, you can just decide. It all starts and ends with exercising your right to choose, one small choice at a time.