I've been taking Centrapeak for about 3 years. I tried another slightly cheaper alternative for about 6 months, but I wasn't getting good results from it. It's a good product, just very pricey. I don't know if it affects testosterone levels the way it claims because so many external and internal factors affect it, but I will say it does help keep me alert and has also helped with my anxiety and my energy levels while working out. As with any supplement, it's not a magic bullet to make up for bad habits and laziness. This coupled with a healthy lifestyle and diet will have the desired results. After not having taken CentraPeak for about 6 months, I definitely felt a little more sluggish and my anxiety was a lot higher, especially during exercise. When I went back to this, my anxiety levels went back down. So, if you are someone who experiences anxiety and sluggishness throughout the day, this might help.