A scientifically unserious instrument that measures how long it has been since you touched grass. Answer honestly, and it will tell you exactly how urgently you need to go outside — then give you an excuse to actually do it.
This instrument applies the peer-reviewed principle that humans are, technically, a type of plant that walks around and needs sunlight. Readings are calibrated against the benchmark of “a golden retriever on a good day”. Accuracy not guaranteed; going outside is nonetheless recommended.