It takes 3-4 days to create a habit, and 7 to break that habit. There is absolutely nothing wrong with watching porn or rubbing one out. Masturbation and fantasy are healthy factors in a great sex life. You shouldn't feel guilty about wanting to pleasure yourself. You know how to get your rocks off better than anyone else. So go ahead rub one out but perhaps instead of just doing it to release steam, talk to your girl about what you were fantasizing about while your were jerking the chain. You might find that she has very similar fantasies and it becomes a firestarter to other things in the bedroom.
Since you say it's not a desire to have sex, I think the problem lies in boredom. Taking up something like pushups is a great idea and does 2 things. It releases your boredom and it gets you into healthier shape. What could be bad about that??
Anyway, don't feel guilty or embarrased about masturbating; you're not addicted, you just have a habit and one that is certainly better than most bad habits out there. If you do feel like it's drowning your sex life then it's a problem.. if you feel that way then go back to my first suggestion. Masturbation and fantasy are alot more fun when 2 are involved
