I see this addiction like gravity. It keeps trying to pull me down. It's not until I get enough distance from it that I start to feel the pull lighten up. Now that I'm clean, it's like I'm in orbit around it. It's not gone, but it's not pulling me down anymore either. Perhaps there will come a day when I no longer feel its effects at all; as if I totally forgot porn existed. I doubt that will ever happen, but I suppose it could.
Anyway, my point is, it only seems hopeless because you haven't stuck it out long enough to feel the pull lighten up. Try to look at it as an experiment; what would it feel like to be totally PMO free for 30 days? You can't know now what you will feel like 30 porn-free days from now; at least not until you're there. So see if you can muster total absolute commitment to 30 days. Then, at then end of it, you will feel the pull lighten - and continuing on becomes easier.
On commitment - it looks like this: I will not use porn or porn fantasy for 30 days no matter what. I don't care how bad I feel, I don't care if I don't sleep, I don't care if I die. I won't use porn or porn fantasy no matter what for these 30 days.
And OSS is right about triggers. In the early days, it's super important to avoid as many triggers as possible. If there is a hot girl at work who triggers you, don't talk to her for a month. If there is a TV show that shows nudity or sexual stuff, don't watch it. Just cut that part of your life out for 30 days as best you can. And when the wrong thoughts arise, just drown them out with a huge NOOOOOOOOOO!!!!!!! like shouting that in your head, then walk away and do something else; shake it up, change the scene. Also, many guys report that they find it easier to reboot if they abstain from masturbation for a while, so you might want to consider that too. In my experience, orgasm triggers cravings which just makes it that much more difficult to quit porn. And in the early stages of reboot, it can be very difficult to masturbate without thinking about porn or porn fantasy anyway...
It's not easy. If it was, no one would be talking about it as an addiction. But it is worth it. You can do it!