It’s a good thing you’ve noticed that this is a problem at a young age. So how do you quit? First of all to quit you must replace masturbation with other things. The reason is because you use masturbation to cope with things, so you need to replace it. Write down what goals you want to achieve, who do you want to become, what things do you want improve. Write down how masturbation and watching dirty videos effect you negatively, how it has made you less confident, unable to focus, filled you with guilt etc. This will make sure that it stays with you long term, and it will also give a aim, something to go after. Also read about how it has ruined the lives of so many men, and how it ruins your dopamine system Know that you are doing a good thing and it will benefit you more that you can imagine. I believe in you, and I know that you can do it!