We're constantly hearing about how important cardio is. For some people cardio is the best part of their workout. And for other people like weight lifters, cardio is their least favorite. So how much cardio is really necessary? For the people who like a slimmer, less visibly toned body, they may consider doing 80% cardio and 20% weight training. Women in particular usually choose to take part in more cardiovascular activity and less weight training to avoid “bulking up” or ha