I know that feeling and if you KCKO, you’ll adapt!
It wasn’t until around the 6 month mark that I could go through a 60 minute taekwondo class without feeling hit by a train. At the 15 month mark now, I break a sweat about 45 minutes in, unless it’s Christmas (ie: immediately gear up for sparring at the beginning of class). Wheeeeeee! We do have an instructor whose specialty is intense bodyweight conditioning exercises, so I’m a puddle regularly after that.
I’m about 50/50 these days going in truly fasted with a tsp of salt, or going in with some coffee/HWC/MCT/glycine/creatine about an hour before.