I really enjoyed the Level Up challenge - I started there (It's under the Beginner's section). I liked that one specifically because they are very quick (12 minutes). You start and you get so busy that you don't notice the time go by and then it's already done! Also, I like that there is a guide that goes along with Level Up - the guide has a calendar in it so you know which workouts to do on which days. The Level Up challenge is 1 month long (5/week). It's also good because you can control the intensity very easily. There are modified versions of everything so you can really ease into it. I'm noticing that as the month has gone on that I'm noticing small little improvements every workout - it's working! Good luck :)