This exercise is a focus-shifting exercise. It involves deliberately tuning in and out of the some of the internal and external experiences that are happening within and around you. Your internal experiences include your thoughts, emotions, physical sensations (including your breath) and any urges that you notice. Your external experience includes anything that you can sense via your five senses, so anything that you can see, hear, taste, smell and touch.
This exercise will help you to develop two important skills for managing your mental health. The first skill is the ability to be aware of where your attention is at any point in time. The second skill is the ability to shift your attention when you want to or when you need to. Being able to consciously choose where you direct your attention. Both of these skills, awareness and focus shifting are key components of mindfulness.