My multi-year long journey of what I learned and getting back to health - which most visibly manifested itself as CFS symptoms (Post exertional malaise) - can be summed up as:
Trusting the therapist and understanding they are not perfect humans themselves. Accepting they are not going to fix me, they are a companion on the journey, I must fix myself with their help.
Going on a journey through all major points in my past and re-experiencing what I'd been through. Whilst having the therapist with me to slowly help unfold the emotions and understand it from a different perspective (i.e. I did not cause the bad things that happened to me, it was not my fault).
This helped me build a foundation, a place of support that didn't rely on other people, which gave me self-confidence to listen to the negative self-talk that I had blocked off for years, because it was too overwhelming to hear. When I started listening to this self-talk, I could then start to converse with it. e.g. "You aren't good enough", "Perhaps I'm not, but let's see what happens when I apply my focus to it", which started taking away its power and effect over me.
Which led me to realising that my intellect and conscious part of my mind is probably only in control of 20%-30% of me. That I'm not a fully logically creature and that I needed to come to peace with my body's needs and messages from my less conscious mind and work together as an integrated whole, rather than trying to force my will based on pure 'rational' thought.
Life has been considerably better since and my decades of depression and low energy have begun to abate.
Whilst the points may seem simple, understanding like this rarely comes from knowing in the conscious mind. It is understanding that has to be understood at a deep level, which is why therapy can take a long time. My favourite way of describing this conscious acceptance but lack of sub-conscious understanding can be summed up as: “I know that, but try telling me that”.