Push-up on knees
Pushups are an effective calisthenic or body-weight exercise that targets your chest, shoulders and triceps. While it is popular with the armed forces and one of the most widely performed exercises in the world, some people find pushups too much of a challenge. You can get many of the benefits of regular pushups by performing this exercise on your knees -- the so-called three-quarter pushup, modified pushup, kneeling pushup or, colloquially, the girlie pushup. With your arms closer it's called a triceps pushup.
This is one of the most basic exercises in any fitness plan. Learn it well !
Detailed Workout Plan
Kneel on your exercise mat and place the palms of your hands flat on the floor shoulder-width apart. Your fingers should be pointing forward. Your arms should be vertical and your hands directly under your shoulders.
Move your knees back until they are slightly behind your hips. The farther you move your knees back, the harder this exercise becomes. Adjust the position of your knees until you feel you are putting sufficient weight on your hands. Do not allow your lower back to sag, as this can lead to injury.
Keeping your abs tight to support your spine, lengthen your neck and tuck your chin slightly in. Inhale, bend your arms and smoothly lower your chest toward the floor. Stop with your chest around 1 inch above the ground.
Push back up to full arm extension, exhaling as you do so. Pause for a second and then repeat. Perform as many repetitions as you can in good form and then rest.