The BFL exercise program is simple at its core, but what makes it so effective are the interval training techniques you’ll be asked to use in your workouts, allowing your body to build strength and endurance rather quickly without the risk of overtraining.


In both our cardio and weight training programs, we reference Rate of Perceived Exertion (RPE) for assessing the intensity of exercise based on how hard you feel you are working on a scale of 1 to 10.

  • 0

    is no exertion at all

  • 2

    corresponds to very light exercise (i.e. walking slowly at your own pace)

  • 5

    on the scale is somewhat hard exercise, but it still feels OK to continue.

  • 8

    is very strenuous. At this level, you have to really push yourself.

  • 9

    on the scale is an extremely strenuous exercise level. For most people, this is the most strenuous exercise they have ever experienced.

  • 10

    is maximal exertion: an all-out, 100% effort – the “High Point”

This scale accommodates a variety of body types and fitness levels, as well as your gradual improvement over time. For some, walking briskly uphill might feel like level 10 intensity, while others may experience an exercise like that at a very low intensity. You’ll find that as you get stronger and fitter throughout your challenge, even your individual intensity levels will change.