You should have seen how the two research pdocs reacted when they realized I had 15 years of detailed data correlating diet, exercise, medications, supplements, and other factors with various facets of my functioning.
There was at first begging, and when I gave them copies, they both left a trail of drool out the door.
Reading old entries, from one or two years ago, I now realize how far I’ve come and how better my mindset is right now !! I used to have a strong victim mentality and an oppressive feeling of doom.
Now I am much more optimistic, but also realistic, I am able to set short and medium-term goals for myself. Such as losing weight - since July I have lost at least 8kg. Or brushing my teeth daily again. Or working on small personal software projects. Or communicating more with friends and family. Every little improvement is important in the grand scheme of things.
I have a hunch that people who hate or avoid keeping a journal/diary are usually afraid of themselves, don’t have the guts to take their fate in their own hands. Of course they might just be lazy
But If you want to reconcile the past with the present, to learn from previous experiences and better understand yourself and your journey, my advice is to start journaling !!