Sooner or later on most days no matter what I am doing (unless already engaged in sexual activity) I will get the urge to masturbate.
Pretty much every time I am perusing and posting on LPSG that is the purpose. Sometimes the urge is inspired by something I am watching on TVs and occasionally it stems from a phone call or e mail etc.
Basically there are a myriad of things that make me want to pull on my penis. I once got so turned on watching these 2 women on a long train journey that I went to the toilet took all my clothes off and masturbated. The removal of all of my clothes made it more erotic for me.