Cardio is a key part to my workouts lately, I typically run a fast paced 2.5 mile run at about 90-80 percent of a sprint. This helps build endurance and will really help lean out the body. I rather do miles over sprints because sprints are harder on the joints and cause more issues with ligaments and muscles. I typically do a 2-4 mile bike ride as well during the day depending on how I feel. I do the bike ride as fast as I can ride, I don't do it to relax or cruise it's fast paced and only takes about 15 minutes to do, so time shouldn't be an issue when biking. The harder you ride the harder you work your leg muscles, it really helps loosen up your legs. I do my cardio before My workouts because it helps you battle fatigue. Doing this will really help with your endurance.