A 53-year-old woman has won  the biggest undivided lottery jackpot in United States history — $758.7 million .

“The first thing I want to do is just sit back and relax,” Mavis L. Wanczyk , Massachusetts hospital worker,  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.

The previous evening, she recalled, she was leaving work with a firefighter and remarked, “It’s never going to be me. It’s just a pipe dream that I’ve always had.”

Then she read the number on her ticket and realized she had won.

Wanczyk has two adult children, a daughter and a son.

The jackpot is the second-largest US lottery prize, ahead of a $656 million Mega Millions prize won by three people in 2012.