The words for practicing abdominal muscles are as follows:

Running (speed is not required, just run for 20 to 30 minutes at a time. This can lose weight)

Sit-ups (it is easiest to straighten your legs, but it is most difficult to bend your legs and put your hands around your neck)

Abdominal muscle wheel (keep kneeling, push the abdominal muscle wheel forward with your hands until your arms are straight and then retract. If you want to increase the difficulty, support the ground with the forefoot.

Pull-ups and push-ups can also exercise abdominal muscles.