I've been mulling this over since you posted and my opinion is:
Changing core beliefs
And
Building a sense of self.
For me, the need for control came I think primarily from childhood messages that I was responsible for other people's wellbeing and therefore I had this omipresence that controlled things. All fabrications of course. But those messages built anxiety and a sense of control and then the need to control.
What added to that was the goal posts kept shifting. The narratives changed as I adapted my behaviour to try and control the uncontrollable. It was never enough. I never got it right. Other people's wellbeing, and my own (which wasn't anyone's concern actually) continued as they were. The messages of what I needed to do to control changed and a never ending mind field of control continued, as did anxiety.
As an adult it was understanding that. Understanding I had no control over anything, never mind how much I believed I did, and that the only thing I can control is my thoughts and my behaviours and, to some extent, my feelings.
And then learning that nothing exists but this moment. Not the past and not the future. Both things that I can't control.
And then learning to change my thoughts.
Not sure I am articulating it all right, but that's my journey with it.