BRAINTREE, Mass. — A 53-year-old Massachusetts hospital worker stepped forward Thursday to claim the biggest undivided lottery jackpot in U.S. history — a $758.7 million Powerball prize — after breaking the news to her employer the way the rest of us only dream of: “I called and told them I will not be coming back.”

“The first thing I want to do is just sit back and relax,” Mavis L. Wanczyk told reporters at a news conference.

Wanczyk chose to take a lump-sum payment of $480 million, or $336 million after taxes, lottery officials said. Winners who take a gradual payout stand to get more money spread out over several decades.

Even after paying taxes on the winnings, Wanczyk is worth more than some small countries such as Micronesia, which has a gross domestic product of $322 million, or the Pacific islands of Palau, with a GDP of $293 million, according to 2016 figures from the World Bank.