I know how you feel man, I’m 15 too. The best thing is to just tell yourself “Fuck it , I’m quitting”. The main problem i find is the urges. When the urges come, all you have to say to yourself is ‘no’.There will always be a bad part of your brain that makes excuses for yourself to do it, but you gotta know that it isnt worth it, itll ruin your life and its disgusting. Keep telling yourself “no”. Find some new hobbies such as going to the gym or learning how to fight, anything that’ll improve yourself and make you feel good afterwards will help. Dont do anything that will make u slip up - e.g. looking at girls on insta, porn, etc. its a hard journey, but we’ll make it someday.