I've never got a good performance early in the morning, and after I get my medicines at 8AM (methyl prednisone included, with cortisol going up as it should) I need a nap.
Even if I'm awake and alert I wouldn't train, it never worked for me and I doubt it ever will.
During law school I'd run at 6AM but that was before going to sleep, I'd been up all night studying and taking care of my grandgrandmother, then run and then go to sleep around 8AM. Some nights I slept through some really bad theory and those times I couldn't even take a walk around the isle: I'd just cruise to my room and collapse like a not fully trained (drunk) toddler (which means sometimes I even missed the bed).
No limits, only my will and the worlds I build.