If you've been avoiding cardio like the plague, this second day of cardio might feel like hell. Believe it or not, these cardio days will actually help you recover, especially at the recommended level of intensity here (130-150 beats per minute).
Think of these cardio days as "active recovery." This low-intensity cardio will pump blood and nutrients to your muscles so they can repair and grow. This workout should actually help you feel less sore tomorrow.
Don't forget: We're bumping up the length of the session by two minutes each day, so you'll do 42 minutes of cardio output training.