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I had been testing out Vi, a set of $249 Bluetooth running headphones with its own built-in AI assistant and biometric tracking features. After a convoluted series of events in which I was offered a potentially illegal entry to the Brooklyn Half Marathon a week before the race, I found my adventure: I decided to run my own 13.1 miles in the Prospect Park Loop with nothing but the AI headphones to guide me, using Vi for a crash training course to prep in less than a week. Vi doesn't offer much more than other running apps I've used: It tracks the distance you run, measures your heart rate, and offers some realtime coaching direction to fine-tune your step rate to find your ideal pace, which it calls your "Comfort Zone," -- but it leaves much to be desired as a next-gen personal trainer. It currently has no dedicated feature to set specific goals, so users prepping for races like me have no guide to train for big events or set more defined goals than just fine-tuning their running style.