Both the above replies are great advice, but I can't help but notice that niether seemed to answer your request. of "how do I stop masterbating." Well when I was single last I did this alot. Well beyond your one or two times a day and I also found it difficult to quit even when I started having sex again.
My advice is to cut back slowly and put limits on how many times a day/week you allow yourself to masterbate. If you simply cannot seem to stop yourself then I advise spending a few days deliberatly staying away from the places you do it most often. In other words limit you oppurtunities to enage in masterbation. Then after a few days test your will power and see if you can resist the temptation, then work from there. It may take some time, but it WILL take some effort.
Llewellyn or one of the other advisers/moderaters may have more information on the health aspect of it all as I admitedly don't know the pros and cons of stopping all together. I myself still do it a few times a week even though I have a live in girlfriend that I engage with frequently.