This wearable worked where a fitness tracker failed me Gymboss' tough little interval timer doesn't collect your data, but maybe that's a good thing.

Bit Timer: A Brilliant App That Makes Interval Workouts Easy This iPhone app is so elegantly designed that, while you still won’t want to work out, you’ll really wish that you did.

Nanosecond interval timers are a critical component in products as diverse as time-domain reflectometers (TDRs), collision-avoidance systems, radar altimeters, and nuclear instrumentation.