Use the results from the testing and user feedback to create a new version of your fitness device.
If your device wasn’t accurate, think about how you might change your code to make it more accurate. Is there something else you can do with the design to improve the accuracy (like placing it on another part of the body or making it more secure?)
Make the changes one at a time and test your device each time to see if it's improved.
Look at your user feedback about the look and feel of your device.
What can you do to improve the device?
Can you make it lighter?
Can you make it more comfortable to wear?
Make a change to the look and feel and then ask your users for feedback again.