Lately, I have switched my cardio workouts to a 15 mile bike ride (at an average speed of 13 Mph) and hill sprints. The workout consists of riding my bike for 7.5 miles, then I do a session of hill sprints by running up a sledding hill, then back on the bike for 7.5 miles. I'm up to 15 hill sprints. Each hill sprint is 40 yds in length and at a 45 degree angle to the top of the hill. After each hill sprint, I walk down the hill.

I have been doing this cardio workout 3 days a week for 3 weeks and I can notice that I am getting much leaner. The workout takes me about 80 minutes. I have to say, that this workout will kick your butt (especially, the hill sprints), but I feel so good after the workout and I am seeing some good results! :)