I actually use my imagination more often than porn. But that's mostly because I'm very picky with porn. Usually when I find something really good, it works a couple times, but then I have to find something else again, and it can take forever. There's only a few things I've found that can work over and over again.
With my imagination, the sexual fantasies are literally limitless. I can imagine things that likely don't exist in porn, exactly as I desire them. I think I got used to it because when I first started fapping, I didn't even look at porn. I don't think I saw porn for the first time until I was 15.