Zumba

Necessity is the mother of invention.

Here's an example from Beto (Alberto Perez), a Colombian dancer and fitness teacher. One day he left the music tape for an aerobics class at home. Instead of cancelling the class, he improvised with a mixture of music tapes from his car, which included salsa and merengue dance music, inventing some new moves to go with the music. The resulting blend was a big hit in Colombia and he took Zumba around the world.

Zumba is a big hit with dancers who have transitioned into personal training.

Here's an interview with Beto, which shows how he's extended the initial product: