No, I lay down on the back, put arms/hands behind my head and lift my head+body till sitting position, then go down, then repeat - so, 40 times easily, till 100 no problem. My BMI is now normal, I've just lost some kilos, but wonder about my muscle tonus.
The question is - does it mean my belly muscles are OK or do I need more training? In case I do - which one? To increase it till 200?
I don't understand what you mean by "if I lay down on the back I could easily move 40 times my body up, could go to 100 if necessary" Could you explain that? Are you referring to lifting weights?
There comes a time when we all should not wear a bikini, but if your belly hangs over your underwear, most likely, you need to lose some of it. Although you can't "spot reduce", good all over exercise and a healthy diet, should help tone the muscles.
Walking is an excellent exercise for overall weight loss and muscle toning; as is yoga.