Elliott Hill starts as Nike's CEO on Monday.NikeNike veteran Elliott Hill started as the new CEO on Monday.Hill takes the helm as the company is facing multiple challenges.Nike said it's aiming to boost innovation and reduce reliance on retro styles for future growth.Elliott Hill became CEO of Nike on Monday, taking the reigns at a time when the company is facing a sales downturn and a struggling stock price.Hill, a Nike veteran who retired in 2020, is tasked with getting the sneaker and apparel giant back on track.