Diana Nyad, the 61-year old woman who attempted to swim from Cuba to Florida without the aid of a shark cage, was forced to abandon the quest halfway between her starting and end points.

Nyad had been swimming for 29 straight hours when disagreeable conditions, shoulder pain, and asthma convinced her to abort the mission at 12:45 a.m. Tuesday.  Strong winds had pushed Nyad 15 mph off course, and after much consideration, she alone made the decision to cut the swim short.

Shortly after making the decision, Nyad boarded the Bellissimo, the 75-foot yacht that carried her handlers, drivers, photographers, and friends and family. She was vomiting as she was brought aboard the boat, but managed to get herself up to a waiting chair where she was given intravenous fluids and a much-needed rest to recuperate from exhaustion.

Nyad's official Twitter account has been posting periodic updates of the swim.

At about 2 a.m., the following tweet was posted: "From Elaine Lafferty on our boat team: It's over. She lasted 29 hours in an heroic attempt."

Shortly afterwards, another post was added: "Realizing the conditions of 5 to 10 knot winds and less than ideal currents, Diana herself decided to end the swim."

A few hours after Nyad boarded the Bellisimo, she held a makeshift press conference before a dozen cameras, CNN reported.

There she explained that shoulder pain had been a problem from the third hour, and asthma became an issue at hour 15. By hour 28, Nyad could only take three or four freestyle strokes at a time before needed to lie on her back to rest and breathe.  At hour 29, knowing she could not maintain the same conditions for another full day and night, she decided it was over.

"I am not sad," Nyad said. "It was absolutely the right call.

"It's hard because I felt like I had it in me. It felt like this was my moment.   I don't feel like a failure at all. But we needed a little more luck."

Nyad attempted the same route in 1978, but after 42 hours was forced to give up the swim in the face of enormous waves.

Susie Maroney -- who used a shark cage -- successfully completed the swim in 1997. The Los Angeles Times said that Maroney's under-24-hour crossing time has called into question the possibility that the shark cage provided additional assistance somehow.

Nyad had expected to complete the crossing in 60 hours. Claiming that "60 is the new 40", the swimmer felt she was in better shape this week than in 1978.

As she prepared to begin her swim in Sunday, she told reporters, "I'm almost 62 years old.... I'm standing here at the prime of my life; I think this is the prime, when one reaches this age. You still have a body that's strong, but now you have a better mind."

Nyad had been preparing for this crossing for years, often with 12-hourlong daily swims.