Need help.

Hi guys, i have had a problem since i was 14 and i am now 24. I cant kick the habit of masturbating, and the shame and guilt i feel the times i loose the fight and give in to the urge affects my faith adversely! Times i cant bring myself to pray for a week or even more because of the guilt. Sometimes i go for a month without doing it and then suddenly i fail....
Please help me.