How to bounceback from Masterbation/porn addiction? How many days it takes to become free and undo the effects of addiction?

Hi, I have been addicted to masturbation since I was 12,I am 16 now. I am skinny fat with Little muscle and a little bit of a good amount of strength left in my body. I want to free myself but I can't. I want to build muscle,focus on studies and become better but I can't. Addiction affects my studies and performing very low in grades. How can I undo the effects of excessive masturbation in a short span of time?how can I become free from this disgusting/useless/garbage addiction. Please help🙏