Not only are hormones released when you masturbate/orgasm but it is also a way of relaxing or soothing yourself when you're stressed or tense. Personally, I'm stressed all the time and if I'm not kept busy my mind always wonders to porn and sex which inturn make me want to touch myself or have someone else touch me.

To help yourself you should see a therapist. You should also consider your job and whether or not it takes up energy or requires you to really focus, maybe you have a lot of built up sexual energy. My advice other than seeking therapy(which may be embarrassing but they've heard it all before) is exercise. Exercise is very good for burning off sexual energy(freud,haha) and also releases similar chemicals.

Those two-four hours you spend take one of them or more and exercise your butt off! At first the exhaustion may cause you to want to masturbate more to relax but if you plan it right you just won't have the time.