When we were trying random things at the onset of my fatigue presenting primary as exercise intolerance, two things made a difference: adderall and an albuterol inhaler. I don't know what the albuterol inhaler does, but it made a big difference in exercise intolerance when I tried it. I don't have asthma. Yet, the more puffs of the albuterol I took, the better I felt during exercise. I tested it up to the max safe dose of 6 puffs. I don't think it is acting is a stimulant. Albuterol was removed from the WADA banned substance list because it after years of debate, it is no longer thought to improve athletic performance.