I have clinical OCD. The actual version not the thing people joke about. I will say because of that I am an expert on living in the moment. Why? Because when it flares up the compulsions result in a battle with attention on your thoughts second by second and wishing to be focused intently on something else so that level of attention has no space to enter. Might sound fun for a vacation but not a place to live. That’s why I’m a software engineer because I can get lost in something and reacquaint my mind with a baseline of attention to attention.
If you want to truly slow time down and live in the moment exercise incredibly hard. Something like a grueling CrossFit workout can make it feel like ten minutes never took so long. Time slows down when each second is exhausting mental and physical anguish to keep your legs pedaling on an assault bike. I love it!