How to do proper classic sit-ups ?
Lie down on your back on a mat with your knees bent and feet flat on the ground, hip-width apart. Keep your arms above your head, with your hands and head touching the floor.
Engage your core muscles and slowly lift your upper body off the ground while exhaling, reaching your arms towards your knees.
Keep your chin slightly tucked and look towards your knees throughout the movement. Do not strain your neck by pulling your head forward.
Pause for a moment at the top of the movement, then slowly lower your upper body back to the starting position while inhaling.
Repeat the movement for the desired number of repetitions. Make sure to maintain proper form throughout the exercise, keeping your back straight and your core muscles engaged.