Here is my report 3 weeks in:
It was fairly easy actually not thinking of porn or jerking off, maybe because I got back to weight lifting/jogging that it preoccupied my mind (I am exercising again because it is work related). However, after 2 weeks in I felt "depressed". My mind was filled with doubt, when I looked at myself in the mirror all I could think of was "not good enough.".
This morning when I got into the shower, I noticed my penis SHRUNK significantly! it was the size and girth of a toothpick! I got out and checked on the mirror to confirm and yes my fear was realized. So I decided to jerk off and not only did I bust a good nut, I penis grew back to it's normal flaccid size and my mood was better. When I got out of the shower and looked at myself and my minimal gains I thought: "good work, keep going." That was 8 hours ago and I still feel ok.

Maybe Semen Retention isn't designed for complete disconnect from sexual urges, but rather to control them in moderation? Or it could be different for everyone. I used to jerk off every other day and never had head "fog" or any weaknesses like that. So maybe some they have the opposite effect that I had.