As soon as I take Ventilean Rx within a couple of minutes I notice a body temperature change. I start getting hotter, more amped and ready for my workout. If I'm tired and I take Ventilean Rx I'm ready to go. I can run for longer on the treadmill without running out of breath. It gives me a lot more energy, a lot more pump, and I've noticed that it's toned my body down. I really like it, and I recommend it.