Situps are exercises where you lie on your back, then sit up to a sitting position and then lie back down again.
Situps are a common exercise for making your stomach muscles stronger.
Examples:
I do situps every morning to make my tummy strong.
She does 20 situps every day to stay healthy.
Situps are good for making your tummy strong.
I do situps, but my cat just watches me.
He does so many situps, he can touch his toes with his nose.
I do situps like a little bug rolling over and over.