If you find exercise boring, you might be tempted by a new invention aimed at helping you to have fun getting fit.
It's a digital pet, called a Fizzee, that you wear on your wrist. But to make sure it stays happy and healthy, you have to keep on the move.
The Fizzee monitors your heart rate and activity levels and the more exercise you do, the happier your Fizzee is.
Designers are now trying to work out whether gadgets like Fizzees really can persuade more kids to get into sport.
There are only four working Fizzee models in the world at the moment and Ben and Olivia got to try them out for Newsround.
Olivia said: "It was really good fun because we wanted to do more exercise so then our Fizzee would grow."
Ben added: "It's like being with another person in the gym, not just on your own."