How to make a simple sit-up shelf at home

Use an old pair of sweatpants, tie the two corners of the pants together and fix them on the crossbar in the middle of the bed leg, and then throw the waistband on the bed. Don't get dressed when you wake up in the morning. Hook your feet on your pants and fix them. Do more than 200 sit-ups first. It is difficult to touch your elbow with your knee. Put your hands on your head and do two waist twisting movements quickly: touch the outside of your right knee with the outside of your left elbow, then touch the outside of your left knee with the outside of your right elbow, then lie down and do the next one.