Waist. The waist is mainly for practicing erector spinae, so you don't need to bear too much weight, and your weight can satisfy yourself. Recommend several actions: goat standing up (the gym has special equipment, which can be practiced on the yoga mat at home), Xiaoyan, and Superman style.
Abdomen. Abdomen can practice belly rolling, anti-belly rolling, flat support, supine leg lifting, Russian rotation and so on. These movements cover the upper abdomen, lower abdomen and lateral abdomen, and the flat support is more comprehensive.
Squat and hard pull can exercise the waist and abdomen at the same time. You can add weight after you are familiar with the movements, but be careful, because it is easy to get hurt.
I hope my answer is helpful to the landlord ~