You can change your fitness goal at any time, by going to the goal screen. If you scroll down to the bottom of your chosen goal, look out for the 'ready for a change?' area.
You can check your fitness level and see if and how it's changed by re-trying the benchmarking workout. You can retry this any time but we also recommend re-doing it every 6 weeks or so, so that you and Hero have the latest and most accurate information about your fitness level. It's a critical way we tailor the workouts for you and make sure they're motivating and appropriate!