In brief, areas of the brain involved in emotional function can become over- or under-active for various reasons. In addition, the activity of the autonomic nervous system that controls many unconscious functions can increase or decrease leading to feelings of anxiety or apathy, respectively. If this goes unnoticed, these can worsen and manifest as mental health conditions that require treatment. It is no surprise therefore that it is considered good practice to be self-aware and practise mindfulness and good habits to keep your mental wellbeing in check.