Exhaustion problem

I always sleep for at least 8 hours in game in order to have max stamina and energy but I don’t get why the character gets exhausted so easily after a a few hours of running the bathhouse. Like my stamina bar is not even at 50% and the red thing that lowers the stamina much quicker starts anyways. This happens even if I eat and have the bar close to 100%. So how do I know for certain when the character is close to exhaustion? Help 😭😭