100 reps all at once or break it up throughout the day. You can do this!
Sit on the edge of a solid chair and hold the front edge of the seat on both sides of your body. Your knuckles should be facing forward, not turned to the sides. You can either plant your feet firmly on the floor.
Push yourself off the seat and lower your buttocks below it until your arms form a 90-degree angle. Then, push yourself back up to the starting position, but make sure not to lock your elbows.
You will likely need to take a few breaks if you are attempting the entire 100 reps at once.
To make it more difficult place the backs of your ankles on a bench, ball or chair in front of you so that your buttocks is suspended in the air.
Kick backs instead: To save your wrists~ standing with a dumbbell in each hand, bend over at the hips to a 45-degree angle, keeping your back straight and elbows in tight by your sides. From a flexed arm position, straighten the arms out and back. You are just bending and straightening the elbow.
Good Luck and Live Well.