Push up is a well-known and excellent exercise for the whole upper body. It strengthens your chest, shoulders, arms and core. You can easily do it anywhere and without any equipment. As you get stronger by doing push-ups regularly, you will have to do either more of them – and that may get slightly boring eventually – or you can make it harder. Try this more difficult variation of a standard push-up. It will challenge not just your strength, but also your coordination, flexibility and balance – all the qualities that you want to perfect for your tennis game.