A compound exercise is one that hits several muscles in one rep. Squats, deadlifts and push ups are good examples of an compound exercise. 

The core is vital to stabilisation and is not only made up of the abs but also includes glutes and the lower back.

Cardio strengthens your heart muscle, which improves your heart's ability to pump blood and oxygen throughout your body. Cardio can also help with weight loss and keep it off when combined with a healthy diet. Having a good cardio routine can help reduce stress and ease symptoms of depression and anxiety. Cardio can also improve sleep resulting in cognitive performance.