Keep the user waiting for 30 seconds with...

So the user has to hold his finger on a device plugged to the iPhone that can feel pressure for 'round 20 seconds, do you got any idea on how to keep the user waiting 20-30 seconds without having him go bored? The actual waiting time varies depending on the user, but it will be roughly around that time. One idea which I don't like is a bird that flies, and the pressure keeps the bird "stabilized". The "game" won't be any vibrations or sound. It's basically a "dynamic" progress bar that gets annoying after a while. And everytime you use the app you have to go through that. The idea I like, is the actual heart-rate monitor. Seeing the pulse in realtime by having your finger on the Device.

Any thoughts?