Feeling Horny

I honestly cannot remember if I ever felt horny on my own in the past without any visual, aural or written stimulant. I suspect I have only ever felt that way as a result of being with a woman or being with P. I have never Md without pictures or stories or videos to stimulate me.
Before I stopped PMO, I belonged to a website called Jackingchat. Some of you may know it. I was always very surprised at the number of men who were excited by their own penis and the feel of it and the sensation of MO. I had never experienced such sensations. The closest I can remember getting is resting my hand on my wife's bottom whilst she was asleep and MOing.
Where's all this going, I hear you ask. Well, it strikes me some men are capable of simply being turned on, without anyone else around and I wonder whether they then use P to prolong that feeling. I always used P to initiate feelings of horniness. I was never horny, then opened up P. I think it might be useful in explaining how some people find rebooting relatively easy, myself included and others fail time after time.
I also wonder whether gay men are more susceptible to this because they are attracted to other men's penises and so must find their own penis attractive?