The feeling and its intensity do fade over time. When, I was a teen, I went through a period of SI. I quit on my own, and have been SI free for nearly 14 years and counting.

I see, SI as an addiction, like alcohol and cigarettes. One can quit and modify their behaviour to cope with the "cravings." The urge will surface at times, so it is important to recognize what your triggers are and address them. (For me, it was a profound sense of powerlessness.) Knowing this will help you respond to those situations without resorting to SI. You must also learn healthier coping strategies. Eg. rubber bands around the wrist, sports, deep breathing, etc...Stopping SI without a replacement strategy will make it more difficult to remain SI free.

Remember SI is a temporary fix. Healthier coping strategies, have no immediate reward, but they do in the long term.

In the beginning, my the urges were stronger and lasted longer, than they are today. Now, they are brief, only lasting a few seconds. I never give in, no matter what. I try to keep occupied and look at the triggering situation in the present, not in the future. The consequences of SI also deter me. Eg. Scars, ER visits, etc...

I have gone a few years, without an urge.

Don't give up.