"I am perfectly capable of agreeing with myself. I don't need anyone telling me what I want to hear." 

Kelly's biggest pet peeve as a NASA astronaut were "yes people," and he demanded that fellow crew members question his decisions.

Team members weren't obligated to air their objections in public, but Kelly insisted that anyone with a differing opinion on matters relating to safety or mission success at least express their view to him in private.    

"A team of people can make a really bad decision"

Following the February 2003 Space Shuttle Columbia disaster, Kelly said NASA committed to improving its decision-making process. 

That tragedy encouraged more horizontal communication by building a new conference room where everybody sat at the same level and had microphones. To further discourage groupthink, Kelly recalled that a saying was put up on the wall: "None of us is as dumb as all of us."  

Kelly remembered those lessons eight years later when doctors were debating surgical options for his wife, Giffords, following the shooting. Given her condition, Kelly said he was his wife's primary caregiver and responsible for making the final medical decisions. 

He gathered all 20 doctors and residents in a boardroom to see what each would recommend.

But instead of starting with the top neurosurgeon – after which his or her subordinates might be dissuaded from providing an honest assessment – Kelly first turned to a very young looking ophthalmologist and asked for her thoughts. 

"The power of the human spirit is an incredible thing."

Giffords suffered from aphasia following the shooting, Kelly said, and had severe difficulty expressing or transmitting language. As the struggle dragged on, it became increasingly depressing for both of them. 

"At one point, I didn't think I had the patience for this," Kelly recalled thinking. "This could be a slow process that lasts forever."

After a month, Giffords was doing well enough that Kelly didn't need to spend every waking minute at the hospital, meaning he needed to decide how much of his old life he wanted to get back.

Notably, Kelly needed to decide whether or not he wished to participate in the final mission of Space Shuttle Endeavor even though flights were dangerous and Giffords was still barely conscious.

Given his wife's full-throated support for his work – she chaired the U.S. House's Subcommittee on Space and Aeronautics – Kelly decided to go ahead.

A few months later, Congress had scheduled a vote on raising the debt ceiling, and Giffords wanted to cast a "yes" vote.

So Kelly said she spent months fighting to get better, and when Giffords walked onto the U.S. House of Representatives floor on Aug. 1, 2011, she received a standing ovation.

"It never got easy for me," he said, "but it did get a whole lot easier."