People with heightened anxiety think too much. While that's useful in creative settings, it's not useful for relaxation. Your brain uses energy, which means you could've been sitting on your butt "doing" nothing for hours but still be totally exhausted if you've spent that time overthinking everything.
I've spoke about this before but I'll remind you that I struggle to stay in the present moment. I'm too busy thinking of all the what-ifs and imagining myself anywhere but right here, right now. It's toughest when I'm walking to and from places in the city. At least an hour or two every day is taken up by walking, where my mind is like a mouse running on a wheel, and I used to think it was wasted time that I've spent thinking about pointless things.
I've recently discovered the magic of listening to podcasts. When a podcast has engaged me, I can walk 40 minutes without thinking of anything else but what the hosts are saying. I listen to podcasts that make me laugh and distract me from negative thoughts or feelings (honestly, there's nothing better than laughing.) I also began listening to podcasts about topics I'm interested in to learn more about them. If I'm going to exhaust my mind, I should be exhausting it with knowledge—not made-up fears.
If you're struggling from overthinking, I highly recommend listening to podcasts! iTunes has podcasts, but there's also a ton of apps to choose from.
Think about topics you're interested in or want to learn more about and do a Google search for podcasts related to that. There's also a sub-reddit you can check out. Or try listening to audio-books on Audible with a free-trial. Find something new, outside of what you learn at work or at school, and I guarantee you'll get addicted to podcasts in no time. Who knows, you might even make your own podcast some day.
Right now, I listen to The Ricky Gervais Show (from the early 2000's), the E&G Podcast (two hilarious guys discuss ABC's reality show franchise The Bachelor #BachelorNation), TEDTalks (there are SO many!), and Muscle For Life (fitness/health podcast with Mike Matthews, author of Thinner Leaner Stronger, mentioned in this blog post.)
I'm still new with podcasts, so commenting below with any suggestions is highly appreciated!