Many users here do indeed use mediation, specifically Vipassana Meditation, me being one as well. The reason many of us use this, and especially this particular type, is that it creates a greater awareness of our thoughts, intentions, and ourselves in different situations and contexts.
And that's important because during a reboot there are many triggers which happen without us fully realizing it until we've crossed the point of no return, or close to it. There are many situations which may seem relatively benign and innocuous, because they don't involve porn or masturbation in themselves, but will nonetheless lead to the point of a relapse if they are indulged in over time.
A phrase you'll see on occasion is that a "relapse happens first in the mind" meaning that we start to indulge in thinking and fantasizing, or just let go of the will to maintain a porn sober mindset. With both my previous long streaks, I realized that I relapsed weeks prior to actually engaging in PMO itself.
But with meditation, you gain a greater understanding of how your mind works, and what is needed to avoid a relapse and maintain a porn sober mind. Meditation also builds a mental toughness to be able to fight and deflect off fantasies with greater resiliency, and not giving into intrusive thoughts, sexually related or otherwise.
There are many different types of meditation.
Here is a good resource on different types which links out to more information in each type. Like I said, I used Vipassana, but have also used in the recent past a tantric form (not sexual though) of concnetration meditation which focuses on a completely void universe; it's pretty effective but not easy. And may years ago,
I read this book on Mindfulness and meditation which is really still the core of my practice.
Finally, I keep
this link as a good reminder. It's from a closed reddit thread from a user who stayed PMO free for over a year and how he went about doing it, how he used meditation, and how it all works. It's definitely very motivating.