The most popular exercise for the abs.
Lie down on a mat.
Your legs should be bent and placed firmly on the floor.
Place your arms behind the head or cross them on the top of your chest.
As you inhale, arch your back a little, stretching your abs muscles. Keep your neck stationary.
As you reach the maximum contraction, exhale and lift up the upper body as if you are crunching trying to bring the shoulders closer to your waist.
Don't move your shoulders.
Reach the maximum contraction of the abs, hold this position for 2-5 seconds and slowly return to the starting position.
Legs, hip, lower back, neck and arms should be stationary.
Don't bring your elbows forward and don't hold your arms behind your head. Thus, it will be easier to do exercise
If the exercise is too easy, you can hold a barbell plate or a dumbbell over your head
To get a better foothold you can place them against the wall or behind a machine.