Cardio is not going to benefit your body composition in the same way as strength training, but it will, as you can guess, improve your cardiovascular health and longevity. Cardio also burns many calories, and a lot more calories per minute, or hour, than weight lifting. This is of course why many people incorporate cardio into their routines to lose weight. It can help increase your calorie deficit, driving more weight loss. Of course, your diet comes first, but cardio can assist, particularly if you hit a plateau.
THE RIGHT WAY TO COMBINE CARDIO AND STRENGTH TRAINING
THE INTERFERENCE EFFECT
Choose low-impact forms of cardio (something other than running, and certainly other than sprinting).
Keep most of your cardio workouts fairly short, with no more than 30 minutes being the general rule of thumb (20 minutes for high intensity).
Split your cardio and strength workouts by at least 6 hours, and try to avoid combing your lower body workouts and cardio on the same day.