In 2015, Ethan Agarwal was trying to stay fit during his business travels. It wasn’t easy — he found it difficult to stay motivated during runs. He wanted an audio-based guide that would be with him every step of the way. Not finding a product that suited his needs, Ethan started Aaptiv. Today, Aaptiv is the top audio-based fitness app on the Apple App Store, and the fastest-growing mobile fitness product on the market.