Masturbation.
Just before turning 12, I was called in for an interview with the Bishop prior to becoming a deacon. One of his questions was if I have a problem with masturbation. I didn’t know what the word meant. I said, no.
Puberty hit me at age 14 and from 14-18 “self-abuse” became a frequent activity. This filled me with guilt and torment. I’d often cry in prayer for God to take away this “unholy” desire that I was acting upon. I thought of castration and even suicide because it wouldn’t seem to stop and I was surely doomed to outer darkness.
I did become sexually actively between 16-18 and felt guilt. But then repented so I could serve a mission. During my stake president interview for my mission papers, I was required to report all sins even if previously confessed to my bishop. This brought up a lot of things I thought I had moved past. And then I was told I had to wait another six months to complete the repentance process. I continued feeling unworthy and weak for years to come.