A shoe wear out sensor includes at least one detector for sensing a physical metric that changes as a sole of a shoe wears out, a processor configured to process the physical metric over time to determine if the shoe is worn out, and an alarm for informing a user of the shoe when the sole is worn out. A body bar sensing system includes a housing with at least one detector for sensing a physical metric that indicates a repetition movement of the housing when attached to the body bar, a processor for processing the physical metric over time to determine repetitions thereof, and a display for informing a user of the repetitions. A system assesses activity and displays a unitless activity value. A detector senses activity of a user. A processor reads sensed activity data from the detector. A display displays the unitless activity value. An enclosure houses the detector and the processor. The processor periodically reads the sensed activity data from the detector and processes the data to generate an activity number, the number being used to generate the unitless activity value based upon a maximum number and a display range.