This is a nice clear example of a well performed press up.
You can start on your knees, but you will need to consciously keep your nose forwards of your hands. It is all too easy to slide backwards when on the knees, and essentially this is achieving nothing. At first you may find you go backwards as you press up. Since we are stronger when we lower ourselves than pushing up, this is understandable. As you get stronger aim to keep yourself forwards of your hands throughout the movement.
So starting knees or toes, as the man says, pull your abs inwards and keep a nice straight line with your body.
Strongly pull your shoulders away from your ears and squeeze your armpits. This tucks the elbows slightly backwards – as Corey does very well on the clip. This action is critical for shoulder stability which will help avoid injury.
You can perform a push up either on your fists, using push up handles or on the palms. If you are on fists or handles, aim to keep the wrists straight. If you are on your palms, press the ends of your fingers into the floor, which slightly raises the actual palm off the floor and helps to unload the strain on the wrist joint. Body weight will be going through the heel of the hand. Feet are about hip width apart.
As you press upwards it helps to draw the abs inwards as if lifting yourself up with your guts. This helps to maintain a long strong back and stops the hips from sagging. It can help to imagine you are pushing the world away from you as opposed to raising yourself away from the floor.
Some say you should look slightly forwards and some say you should look downwards. Whichever you choose, it is very important that the head doesn’t sag down.
Do remember to breathe! The natural breath is in on the way down and out on the way up- or out with the ‘effort’ of the press UP.