Havana, Cuba (CNN) -- Diana Nyad is making good progress in her latest attempt to swim to Florida from Cuba, her crew said Sunday.
"There's no stopping her now," the crew said on her blog.
After jumping into the waters off Havana on Saturday afternoon -- a day earlier than originally planned -- Nyad had swum nearly 28 statute miles as of Sunday evening, putting in 50 strokes a minute, her blog reported.
The full distance to Key West, Florida, is 103 miles, a trip expected to take Nyad 60 hours if the 62-year-old is successful in her attempt -- her fourth.
"I feel I have a lot more energy but I'm conserving," she said, according to a message posted on her official Twitter feed.
Nyad was reported to be "comfortable" and "confident" after a difficult first night in the water.
She was stung by jellyfish on her lips, forehead, hands, and neck. Some stings were from box jellyfish, her blog said.
"Cheered by her crew as she swam toward the side of her escort boat, Voyager, for a feed this morning, she gave the thumbs up" and asked how the crew was doing, according to her blog. "Today is more like swimming," Nyad said in a quote on the blog. "I don't know what you would call last night -- probably surviving."
An "unfriendly" one-foot chop of waves made her swim tougher overnight, the blog said, but at "present the current is no longer against her."
She began the swim a day early because the water seemed to be "fantastic," Nyad said at a news conference before beginning the swim. Her Xtreme Dream team "Has been brainstorming and thinking, 'We've got to get out there,'" she said.
Nyad's first attempt to cross the Straits of Florida was in 1978, when rocky seas left her battered, delirious and less than halfway toward her goal.
She returned to the effort twice last year. She was done in once by an 11-hour asthma attack and was later thwarted by box jellyfish stings.
Nyad insisted she was ready to try it again now, and acknowledged Friday, "I'm feeling tremendous inner pressure that this has got to be it, this has got to be the last time."
She's in the water without a shark cage, relying on electronic shark repellent and a team of divers to keep them away.
In the 1970s, Nyad won multiple swimming marathons and was one of the first women to encircle the island of Manhattan. She holds the world's record for longest ocean swim -- 102.5 miles from the island of Bimini in the Bahamas to Jupiter, Florida.
Nyad says she was 8 years old when she first dreamed about the possibility of swimming across the Straits of Florida. At the time, she was in Cuba on a trip from her home in Florida in the 1950s, before Fidel Castro led a Communist takeover in Cuba and its relations with the United States soured.
"I used to stand on the beach and I said to my mother, 'I wonder if anybody could swim over there," Nyad recalled saying, while pointing to the Keys.
In her 60s, she says, she still feels "vital (and) powerful" -- and definitely "not old." A successful swim ideally will inspire people her age and older not to let their age hinder them, Nyad said.
"When I walk up on that shore in Florida, I want millions of those AARP sisters and brothers to look at me and say, 'I'm going to go write that novel I thought it was too late to do. I'm going to go work in Africa on that farm that those people need help at. I'm going to adopt a child. It's not too late, I can still live my dreams,'" she said.
CNN's Matt Sloane contributed to this report.