Just came here to say this, as someone who is visiting gyms for nearly 2 decades now and who has failed several times in launching whatever-fancy-app-product:
WOW!
WOW!!
WOW!!!
not only did you create something (thats step 1), you created something that works (you released a working version, clap clap), you created something with a real usecase (not the next get-rich-crypto-bro-app), AND:
from your current version, i see gazillion ways of extending/expanding the product.
Keep going - dont listen to the others :)
(if you think about monetization: Just watch a couple of these fitfluencer channels, and you will get tons of inspiration - also out of sport-channels, you will find lot of marketing ideas)