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.
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.