Cardio, also known as aerobic exercise, targets your heart and lungs by using free oxygen in your body. Your heart is a muscle and like any other muscle the more you exercise and work it,  the stronger it becomes. Your lungs benefit greatly from this mode of exercise too:  

Aerobic exercise can:  

• Reduce body fat  
• Relieve stress  
• Help to lower your blood pressure   
• Aid better sleep  
• Give you more confidence in appearance  
• Reduce the risk of heart disease  

There are many forms of training sessions and routines you can follow, ranging from HIIT training to Circuits. The aim is to condition your body at high intensity through resistance or endurance. Circuit training is a great way for people of different levels to participate together, all working to their own personal level of ability. High Intensity Interval Training (HIIT) is another form, using an intense level of exercise, for shorter recovery periods. Each exercise is repeated to a predetermined number, stressing a particular muscle group.