I researched Force Factor and felt that it was a product that I should try. I am 54 years old and was working out sparingly. After using Force Factor for about 3 weeks I noticed an improvement in endurance. I was doing 3 sets of my weight lifting routine every other day and was quickly able to go to 4 sets and add additional weight to each exercise usually a 5 to 10 % increase in weight. Now after 60 days I have increased all my workout weights by 20%. And after an additional month I have added a 5th set to my routine and have gone from 25 minutes of cardio every other day to 35 minutes with a great pump and feeling good after the workout instead of exhausted. Also, I am now able to recover quicker and I am working out 7 days a week alternating weight lifting with cardio every other day. I have not noticed any side effects as long as I consume plenty of water throughout the day. The product seems to be most effective when taken about 60 minutes before your workout. Over the last 60 days I have added an inch to my chest and a half an inch to my biceps and increased my energy level tremendously. My girlfriend says Honey, you look great. Thank you Force Factor for the great product!