Nov. 14, 2011— -- Rep. Gabrielle Giffords has always been a fighter.
For years, she fought for her causes in Congress, she fought her way through 10-mile-hikes and runs with her friends in Tucson, Ariz., and with her husband, astronaut Mark Kelly, she fought -- through in vitro fertilization and fertility drugs -- to have a child.
But on Jan. 8, all of that changed. Following the shooting of 19 people at a meet-and-greet in Tucson, Giffords fought to survive a near-deadly gun shot to the brain, and after that, she had to fight once again, for the life she wanted back.
"Difficult," Giffords says in her first interview since the shooting, with ABC News' Diane Sawyer.
Giffords still struggles for the right words to form sentences, a condition called aphasia that is common in brain injury patients. She has undergone months of intensive speech and physical therapy to try and rebuild the connections in her brain that were severed when a bullet entered just over her left eye, traveling through the left side of her brain.
"It's clear that any lower, it would've killed her, any further midline, it would've killed her," Kelly tells Sawyer. "If it crossed hemispheres, it would've killed her. Any further outboard, she'd never be able to speak again. Any higher, she'd never be able to walk."
Giffords' remarkable journey to recovery and the love story that brought her and Kelly together is the subject of a new book they worked on together, "Gabby: A Story of Courage and Hope."
In the beginning of the book, Kelly writes that he and his wife hoped that 2011 would be "the best year of our lives." Kelly would command the last flight of the orbiter Endeavor, Giffords would begin her third term in Congress, and the two would hopefully conceive a child together.
Instead, 2011 was punctuated, first with terror and grief -- and then with a daily routine of hard work, occasional setbacks and personal triumphs. Together Giffords and Kelly, a couple bonded by a deep and lasting love, learned what survival really meant with a severe brain injury.
"She was sitting in her wheelchair, tears running down her face. She was hyperventilating, absolutely panicked," Kelly told Sawyer. "I saw how scared she was. I got scared too.
"I just held her, and said, you know, we'll get through this," he said.
Watch the Full Diane Sawyer Special "Gabby and Mark: Courage and Hope"
It is that determination, along with Giffords' own personal strength that shine through in exclusive home videos taken by Kelly and their family that will be seen for the first time as part of the Diane Sawyer special. In one video, taken a mere two and half weeks after the shooting, a once-talkative and enthusiastic Giffords is seen working with her speech therapist and Kelly to relearn how to speak and move.
"All right, how about that thumbs up?" Kelly asks in one clip. Giffords, struggling, finally raises her index finger.
"That's one finger, but how about this one?" he asks. She responds, raising her thumb slightly, fighting her way through the pain at the sound of Kelly's voice.
"Yeah!" He cheers. "That's it! That's a thumb!"
Kelly and Giffords' family decided to document every milestone of her recovery, realizing some day Giffords would want to know what had happened to her. Every moment of progress, no matter how small, is seen as a huge step in the tapes.
In another video a therapist is shown chanting "I love you," to Giffords, who struggles to chime in with the word "you." It is an occasion for cheers.
The videos also show the importance of music in Giffords' recovery process. Because of the damage to Giffords' language pathways in the brain, from the very beginning of rehabilitation therapists would use songs as a different way to retrain her brain.
Gifffords would sing a variety of songs, everything from Tom Petty's "Free Fallin'" to "Tomorrow" from the musical "Annie." The songs also offer a chance for moments of levity and fun in what could often be grueling rehab sessions.
Learn more about the role music can play in the rehabilitation process.
Kelly tried to extend that light mood as much as possible for his wife's recovery, posting a "No Crying" sign on the door of Giffords' hospital room. During therapy, Giffords cracked jokes when she could.
"Gabby, you sit in a, what?" the speech therapist asks Giffords in another home video.
"Spoon. Chair. Goofball," she says quickly, laughing.
"Did you just call yourself a goofball? Goofball Giffords?"
"Yes," Giffords answers, laughing.
Another time, when they'd been joking about hyphenated names, Kelly walked into the room and Giffords looked up at him.
"Giffords," she said, her therapist and husband looking at her in confusion. "Mark Kelly-Giffords."
"Kelly-Giffords? No. I'm not changing my name. Ain't happening," Kelly said, to everyone's laughter.
That positive attitude, which Kelly said was his favorite thing about Giffords when they met, helped her learn to walk and speak again. Though Giffords was severely injured, and is only just now beginning to step back into public life, she and Kelly are considering a run for reelection next year -- if she can. It's a decision, he says, Giffords will make by May 2012 -- the filing deadline.
In the last page of the book, the only chapter written in her own voice, Giffords says she wants to return to Congress and to work for the American people if she can.
"I will get stronger," she writes. "I will return."
Kelly, always the supporter, says he thinks she can recover enough to serve once again.
"She doesn't give up," Kelly says. "If that's what she wants, that's what I want for her. You know, I think she has the right to a chance to recover. She was elected by a lot of people who voted for her in Arizona. When she knows she's ready, she'll make the decision."
Kelly's faith in his wife's recovery is a sentiment shared by many of the doctors who have worked with Giffords.
"I think she'll continue to recover… throughout her lifetime," says Dr. Nancy Helm-Estabrooks, Giffords' Speech Pathologist and Professor Emeritus, Western Carolina University. "I'm not putting any cap on her. I can't begin to think far she might go."
Kelly also hopes that within the next year Giffords and he will be able to make a decision about whether to attempt once again to have a child together.
"Gabby and I hoped that 2011 would be the year we finally could have a child together," Kelly wrote. Giffords had been undergoing fertility treatments with a doctor in Washington, with whom she had an appointment for the second week in January, just days after the shooting.
Kelly said he still hopes that they could have a child together and they are keeping many options open, including surrogacy.
"It's something we will continue to talk about, and I think we'll know when the time is right. It's not today, but it could be a year from now," he said.
Giffords, however, is still undergoing therapy -- two hours a day at home -- and trying to improve her speaking skills. Her hope, she writes in the last chapter of the book, is to speak more fluently. While doctors say she can comprehend everything going on around her, she still struggles to express what she wants to say.
"Better," she says in the interview, when asked what she wants more than anything right now. "Better. Better. Working hard."
Every day Giffords tackles new challenges, encouraged by the fact that Kelly will always be by her side.
When asked if there was one word Giffords would use to describe her husband, she told Sawyer it would be "brave."
"That's what I think of when I think of you, too," answered Kelly, a true partner in the road ahead.
Click here to pre-order Gabrielle Giffords and Mark Kelly's new book "Gabby: A Story of Courage and Hope"