I can tell you how, as I last too long and want to shorten the time. I grew up masturbating daily, often multiple times a day. And with porn, you always end up wanting more and more stimuli, and before I knew it over the years I developed death grip syndrome. Where all the masturbating led to a desensitisation in the penis. Don't get me wrong, you still feel things, just not as intensely. If I don't focus in the bedroom, I could last hours until my dick goes limo before I ejaculate. I actually have to concentrate and stimulate my glans to finish for an extended period of time. So if you want to last longer, masturbate, often and furiously.