I only tried this supplement because I was given a sample of this during one of my orders (it was the only free sample option there was). I wasn't exactly sure what I was gonna use it for, but I decided to take this before one of my cardio days. After taking this about an hour before my workout, I could actually feel an improvement in bloodflow and for me, breathing. This obviously helped enhance my mood and gave me a good sense of energy. I had one of my best runs in a long time. I cannot guarantee that my workout was solely a product of this supplement, but I would definitely try it again if I was given more free samples.