How do I change the UI from the WearableListenerService?

I know this question has been answered several times, but being new to Android I still can't figure out the answers. In this question, for example: How do I use an Android handler to update a TextView on the UI thread? and then there is a question where the answer is also very unclear: Using the Data API to update the Watch Face UI .

I have a MainActivity.class that has a RadioButton that shows if the phone is actually receiving data from Android Wear sensors. The service that starts receiving data is called MyService and extends WearableListenerService. All I have to do is set the RadioButton to true or false depending on the boolean value that I control in MyService.class.