What is it?
A yoga mat.
What are they doing?
They are doing a spinning class.
What is he doing?
Lifting weights.
What is she doing?
She is doing pilates (or yoga).
What is it?
A cross-trainer.
What is it?
An exercise bike.
What is she doing?
She is doing stretches.
What is she doing?
She is doing aerobics.
What is it?
A rowing machine.
What is he doing?
He is doing press-ups.
What is it?
A running machine or treadmill.
What is he doing?
He is doing sit-ups.