Facing a table or chair, place your hands shoulder width apart on the edge.
Take a large step back and place both feet together.
Now lower yourself down, until you are just about to touch the table with your chest.
Pause, then raise yourself back up and repeat until your arms are too tired to continue.
The movement should be difficult, but if you are unable to complete it, find a surface that is higher, move your feet in closer, or only lower as far as you can go.
The more often you do this exercise, the stronger you will get. Lower your position as you get stronger to challenge yourself