Three years ago, she was in a supermarket parking lot in Tucson. She was engaged in the most meaningful act in political life, talking to the people who had sent her to Washington. Then a bullet pierced Gabrielle Giffords’ brain.

The Arizona congresswoman was one of 18 who fell to bullets that day. Six would die.

Wednesday, she jumped from an airplane with a sky-diving friend, another leap in her defiant reach for a life that came so close to ending. And she served notice that she will apply the determination that has marked her personal rehabilitation to the fight for gun restrictions that has been her public pursuit for the past year.

Giffords, 43, left Congress in 2012 to gain more time for recovery; her seat is held by Ron Barber, a former aide also shot that day. One year ago, after the shooting at an elementary school in Newtown, Conn., Giffords and her husband, Mark Kelly, formed Americans for Responsible Solutions, a group advocating what it terms reasonable answers to gun violence. By some measures, her rehabilitation has gone better than her gun control efforts, but Giffords said Wednesday she would persist on both fronts.

“This past year, I have achieved something big that I’ve not spoken of until now,” she said in a commentary published Wednesday in the New York Times. “Countless hours of physical therapy — and the talents of the medical community — have brought me new movement in my right arm. It’s fractional progress, and it took a long time, but my arm moves when I tell it to. Three years ago, I did not imagine my arm would move again. For so many days, it did not.

“I did exercise after exercise, day after day, until it did. I’m committed to my rehab and I’m committed to my country, and my resolution, standing with the vast majority of Americans who know we can and must be safer, is to cede no ground to those who would convince us the path is too steep, or we too weak.”

“Our fight is a lot more like my rehab. Every day, we must wake up resolved and determined.”

The latest policy moves came last week, when the Obama administration announced new rules that would bring more mental health records into the federal background check system employed during some gun purchases. While the new rules could have blocked purchases in at least one high profile case — the 2007 Virginia Tech massacre — they do nothing to expand the types of gun purchases that require background checks.

On the anniversary of her shooting, Giffords merged the political and the personal. In her commentary, she called on Congress to pass proposals that she said represented consensus: making it illegal for stalkers and domestic abusers to buy guns, extending mental health resources, toughening penalties for gun trafficking and strengthening the background check system.

But on Twitter she struck a more reflective tone. “Progress has come from working hard. Today, I grieve, I remember, and I take another step. I’m stronger now.”