Nature deficit disorder is a term used to describe how people feel when they don't get to spend enough time outdoors. It's like missing out on fresh air and sunshine, exploring nature, and seeing beautiful things. It's not actually a disorder, but more of a feeling. People who spend more time indoors and less time outside may feel disconnected from the natural world, lonely, or even depressed. They can also miss out on the physical and mental health benefits of getting enough physical activity in nature like stress relief and stronger immune systems.