Dr. Im 19years Old..i Havebeen Shaking Everyday My Penis Since

Dr. Im 19years old..i havebeen shaking everyday my penis since i was only 13 years old..i want to stop my self from doing it.. And i have tried to stop it so many days.. After 1/2 days i can't able to control..i had to do it agin... I just cannt understand how to get rid from this habit... ??? Will you please give me some advise.. ??