All new music is basically copyrighted. But as long as your gym pays the ASCAP/BMI license fees, you should be good to use any music you like.
I struggle with acquiring sports equipment for lessons (https://www.bestadvisor.com/yoga-mat) I also find it troublesome to find appropriate music because of copywriting rights…..
One of my biggest struggles is weeding out folks like you trying to sell stuff while presenting as helpful. 🙂
It’s a total time suck.