A bit worrying that she measured change by using an "online personality test to assess where I currently scored on the Big Five".

I do believe that we can change our internal responses by slowly teaching ourselves to respond differently.

However I also believe that thinking about thinking is a dangerous activity. The risks are training yourself to be neurotic, and a habit of overthinking.

We can use our rational minds to change our irrational responses.

However how many people are skilled at teaching themselves? We could look at how good they are at teaching others (especially emotional kids).