This was the case for me too! :) I really hated running at the start because it triggered anxiety. In the end it turned out to be a blessing because it provided me with basically a safe (not socially connected etc) way to activate it at my own comfort and degree I was comfortable with and basically feel like my twisted up brain connections got smoothed out by doing it for a while. (Basically exposure therapy as you mention.) Lions mane may have been part of helping too but idk.