I was skeptical about how my arms could be "transformed" in 21 days, especially with a rest day every other day, but OMG the difference is night and day! I went from completely flabby arms to seeing definition and the start of leaner arms in 21 days!
Step 1 for getting back into running after baby! The time to start is NOW! Whether you've had kids or not this will get you moving in the right direction with these walk / run intervals. This is only Step 1 of there's more.