The LivingFit course allows you to log activity for the current week, and the previous week only. If you are looking at your current week, or the previous weeks activity log, the weekly video needs to be completed. 

To begin, click on the arrow to start the weekly video. Once the video is complete, the activity log link will become available. 

The course is considered complete after you reach a total of 9 weeks of activity. You have 12 weeks to reach this goal, allowing you to miss up to 3 weeks for flexibility.