Brock puts on the 40lb weighted vest he wore cycling across Canada (http://www.biketobeatobesity.com),
and squats for 10 minutes straight, to give his legs a good shock.
Try throwing 10 minutes of squats into any workout to shock your system.
Marta and Brock incorporate body weight resistance exercises during their afternoon bike ride. The exercises can be done anywhere and up the intensity of the workout.