I just happened upon the Erin O'Brien workouts one day and since they had great reviews (thanks to all who took the time to write a review) and they were remarkably inexpensive, I purchased them both - (Strong Body Fit Body and Strong Body, Ageless Body with Erin O'Brien on a whim.I've been exercising for years and would rate my fitness level as intermediate. Now in my mid-50's, I'm very interested in maintaining my health, but am aware I need to focus on exercising in ways that won't injure or damage my joints, but will protect and possibly strengthen them and I believe Erin O'Brien's DVDs do that.After using the Strong Body, Ageless Body over a few weeks, I tried Strong Body Fit Body and found it much more challenging - but not to the point of being ridiculous. It is recommended women start out with 5 pound weights and work up to 8 pounds, with the recommended starting weight for men at 8 - working up to 10 pounds.The cueing on the exercises is excellent, giving informative instruction on form and what muscles are being worked - and breathing tips. Occasionally she'll tell you what form mistakes not to make, helping you to increase your effectiveness and to avoid injury. While the routine has enough intensity for it to be a cardio workout, it is easy to follow. Erin introduces you to the combination moves in steps often starting out slowly so you can learn and perform the moves with proper form, but it's never confusing. I like her coaching style, which is calm, encouraging and motivating without being either a drill seargant or too perky. She makes you want to make it through the whole set, acknowledging that it's tough, but that you can do it.There are a few high impact exercises (which help boost the heartrate and give a cardio effect), but they're spaced far enough apart that they weren't a problem for me, even with my cranky feet. I was sweaty when I finished the workout, but felt energized instead of wiped out afterward. Overall, there is nothing in these workouts that make me concerned that I'm going to injure myself.I like these two workouts so well I wish there were more - and will definitely buy any others that she releases - and I highly recommend both this and Strong Body Ageless Body.