What I would do first, is go to an Apple store and have them run a battery diagnostic on the Apple Watch or they can offer a diagnostic over the Phone via connected Bluetooth from iPhone if you don't have a store in your area. It's free and then they can direct you from there if there's something that needs to be repaired or replaced for a future Genius appointment.
I don't mean to derail the thread, but what kind of workout do you do on a daily basis? I also workout approximately an hour and a half to two hours a day, every day, just curious what you do for a routine?