Science has found that the best course of action to getting a lean, healthy body for yourself is to tackle a combination of both weight lifting and cardio training. For many people, this means legging it out on the treadmill or elliptical alone is not going to give you the results you want. In fact, if you want that defined, chiseled look, then sooner or later you're going to have to either lift some dumb bells or start sweating on a weight machine too.
So now you know that you have to do a bit of both for a balanced, healthy body and look. The next questions to consider though are: how much of each do I do and what comes first? Great questions that again science has taken a crack at answering for you. It turns out that when you need to cram both weights and cardio into a single, sweat-driven session, weight lifting should kick things off.
According to both anecdotal evidence and scientific testing, it benefits your body to do weight training first because your body then has sufficient energy to complete challenging repetitions. In one study, researchers tested three workout routine variables: weight lifting alone, running then weight lifting, and cycling then weight lifting. They found that the participants who did weight training alone, with no cardio beforehand, successfully completed more repetitions than those who put in a cardio session first and then hit the dumb bells.
Part of this is due to the fact that cardio creates muscle fatigue for the very fibers you need to do resistance training, as a result of your form and energy levels to complete repetitions will suffer. However, do not think that putting time in on your bicycle or elliptical is unnecessary useless. While strength training will speed up your metabolism, helping your body burn fat faster, cardio is important to help you actually slim down while strength training focuses on adding muscle. So you make saying to yourself, “OK, do weights and then cardio, I got it. But what actual exercises should I do?”
If you're built to have exceptional cardio capacity, then perhaps long-distance running will work best for you. Filled with those quick twitch muscle fibers that effect anaerobic exercise like weight lifting? Then traditional bench press and curls may be what you need, or maybe something even more intense like kettlebells, martial arts, any variety of exercises.