You might have built up a tolerance to it. That happens often with stimulants. But then you have to take more to get the same effects as before.
It sounds like you have put your mind to not taking any medications for energy. That is good, there are other ways to get your level of energy up and I think walking really helps.
Start out slowly and work your way up. It increases energy and clears the mind. I highly recommend it.
Best wishes for a wonderful day.
Moderator-Depression and fibromyalgia
fibromyalgia, Chronic fatigue, depression,allergies