You can attach a photo to the desired activity by clicking on the desired Activity and tapping on edit on the top right corner. From there, you can attach a photo by taking a photo or choosing an existing photo. When your selected Activity is due, your clock (or "O") will display your Photo Note in the center. It will remain there for the duration of your selected Activity. This is great for motivational content around exercise or Nutrition! Your photo-attached notes are also available on the Apple Watch.