Well I got my sample yesterday. Today I used it pre-cardio. I took 2 pre-workout. I really didn't notice much at all as far a energy. What I did notice is increased concentration. I would use this product more as a nootropic than a thermo. I did like the effects though, I just wish they were more pro-nounced. My cardio workout seemed more difficult, but it also seemed as though I worked harder and got more out of it. I would purchase this product but I wish it came with a 30 day supply or more. Say 240 caps per bottle for around $35. That way I could take 4 pre workout and 4 others spread out evenly through the day. 2 at a time after my initial pre-workout dose of 4.