“You want to be reinventing when you are healthy, you want to be reinventing all the time,” Jassy, 53, said in December at a company forum. “You have got to be manancial and relentless and tenacious about getting to the truth.... You have to know what’s working and what’s not working.” He cited Netflix’s decision to cannibalize its own DVD rental business in favor of streaming. The focus on the future is fitting given Jassy’s career is defined by his leading Amazon into a wholly new market: cloud computing. Amazon Web Services rents space and software programming for customers to run their technical operations on the company’s servers. The arm now fuels Amazon’s profits and dominates the cloud market just as the company leads the world of e-commerce. Jassy, who joined Amazon after graduating from Harvard Business School, worked as a technical assistant for Bezos in the early 2000s and was instrumental in leading the company’s push outside of book sales. ADVERTISEMENT Jassy’s rise to the top job looked clear after longtime executive and consumer chief Jeff Wilke announced his retirement after more than two decades with the company. Wilke was Amazon’s second most high-ranking official along with Jassy. His attitude of embracing change also made him a favorite. At the same speech in December, Jassy noted just 83 of the Fortune 500 companies from 1970 are still on the list -- and only half are on the list from 2000. “It’s really hard to build a business that sustains for a long period of time,” Jassy said, adding, to stay on the list, he said, “you are going to have to reinvent yourself” and often more than once.