Patricia,
If you want an intense workout for 20 minutes, YOU MUST TRY Cathe's Maximum Intensity Cardio. It will be the most fun, yet intense, 20 minutes of your life! It is a real blast!! The music is very good and motivating. Believe me, this video will make you want to get up and move. There are 2 sections to the video. First you begin with 20-25 minutes of hi/lo floor aerobics, then you move on to the step section (for approximately 25 minutes). I have never even made it to the step section because the hi/lo wiped me out. I have sat and watched the step section and it looks real fun. I used to run in the past, and I betcha this video would help to improve your running (of course, you might not need to improve, but in case you're looking for increased running speed, I betcha this video would be of great help). Can't say enough good things about MIC. Hope you'll give it a try!
Lisa Seymour