Reading between the lines, this definitely sounds like a form of sex addiction that you're experiencing. Any kind of addiction is best tackled with professional help, and second best with the help of friends. I would strongly suggest in addition to seeking professional help, also talking to your friends saying "hey this is something I'm struggling with" and if they can be accountability buddies that's even better!

Any addictions I've kicked and lifestyle changes I've made have been most successful by slowly adjusting. Quitting cold turkey is the easiest way to fail. Unlike my changes which were kicking coffee/caffeine, and reducing screen time, yours is is a perfectly healthy process gone awry, so your goal may not be complete elimination, but just a reduction back to a healthy level. You seem reluctant to share your current baseline, and I won't push, but the easiest place to start is to say "I can wait another 20 minutes before I do that" and put it off a little, and just keep putting it off a little longer.

Maybe you might find doing a healthy habit every time you feel the urge to musturbate helps, such as doing 5 reps of a calisthenic exercise (excercise is also helpful in redirecting the blood that would otherwise be headed south!) or drinking some cold water (when I was quitting coffee I'd put my glass of cold water right next to my coffee. Every time I would reach for the coffee, I'd redirect my hand to the water and only go for the coffee if I still felt I needed it after the water, which most of the time I didn't!) or maybe you're just needing something to do with your hands and that's how you end up masturbating some of the time. In that case, have you tried investing in some kind of fidget toy? Maybe try keeping that in your lap so every time you find your hands going for something to fidget with you can move to the fidget box or whatever instead.

It's all about slowly shifting your normal, the same way that habits are formed just in reverse. It's not going to feel like you're making a big change at any point but tracking progress can help. Keeping a daily log of how many times you masturbated, when and for how long can help to see the trend. I would also suggest including the consumption of sexual content in that log. Just like masturbation it is perfectly healthy and fine for adults to consume sexual content, but too much of anything is going to be bad for you, and you'll probably want to figure out your current baseline and goal for that as well.

Small steps can make a big impact in the long term. Just being able to set a small goal each day of "I'll wait a couple more hours before I do that" or "maybe I'll tackle cleaning today's dishes before I rub one out" can add up faster than you might think. When I was quitting coffee, reducing from 64oz per day down to about 12oz per day only took a few weeks of active effort and was relatively easy with these methods, but eliminating down to zero took actual commitment. Reducing my screentime also took a few weeks to adjust the habits and baseline so that now I reach for a book or go work on a project instead of playing a video game for 4 hours. I haven't pushed it to zero and that's not my goal, so I'm close to where I want, I just have to keep this new baseline for a while so that it sticks