If you do this exercise you will see change in 4 minutes. When you do sit-ups you are toning the muscles not the skin.
What tones the skin as well as the muscle is the opposite of the sit-up which is an extension not the flexion.
You can stand up and do a stretch.Stretch by leaning backwards while tightening your stomach and butt muscles.
If you have back pain, you might want to do this very lightly.
Go back and forward about 25 times.
You’re going to rest for 30 seconds and flex your back forward or lean forward then do the exercise again.
Think about it, what people do during sit-ups is flexing over and over again but they’re not toning the skin superficially or anything on top of it.
You are going to do 4 sets of 25.You can do every other day.
As you get use to it, you can do more and more to the point where you are doing 50 sets.