If you want to reduce how often you masturbate, it might be better to go at it from a more positive angle instead of a guilt/shame/"oh-I'm-a-sinner-I-must-STOP-forever!" angle. When you get the urge, tell yourself, "If I skip this time, it will be better next time." If you let the urge build for a while, even a few hours, there's the promise of the experience being better later. Isn't an orgasm stronger if you haven't had one for a longer time? I'd probably say you could cut yourself to twice a day at first, and down to once a day eventually. Baby steps.
Of course this might be easy for me to say. I'm not a guy and my sex drive is extremely weak even for a female, so I can't reeeeally know what it's like to live with constant sexual tension. For a 16-year-old boy to stop altogether is going against nature, no matter what that Big Punitive God in the Sky says.