Tracking an activity allows your coach to see that you have / have not completed it. It also lets you keep track of your progress, both in your schedule and in your streak on the ‘Me’ screen.
Select an activity (in this case, ‘A delicious breakfast’) in your schedule
Click on the green button - ‘Track activity’
Provide feedback and click on the green button - ‘Submit’. Your activity will now appear as tracked, in your schedule.