The centre-back has enjoyed an emotional return to Argentina's starting line-up after overcoming injury problems that kept him away from the national team for 598 days.
Preparing for Friday's World Cup last-16 clash against Cape Verde, Martínez spoke to FIFA about his football philosophy, Lionel Messi's influence and the responsibility he feels every time he wears Argentina's shirt.
"My game is to go for every ball like it's the last.
"I try to transmit that, to compete and for the fans to feel represented."
That approach has become one of the defender's trademarks since arriving at Manchester United.
Despite injury setbacks over the last two seasons, Martínez has consistently earned praise for his aggression, commitment and willingness to put his body on the line.
The 28-year-old also reflected on the pride he takes in representing Argentina.
"Coming from where I came from is part of what allowed me to get where I am today," he told TyC Sports.
"I'm grateful for it every day and I try to stay aware of that. I enjoy it and give everything for our national team and for representing Argentinians.
"Our national team has a connection and a unity, not only among ourselves but also with the people. You can feel it."
"And with Leo, having him makes you better, he makes the whole team better. It gives you confidence and makes you give your life for the team. He leads by example. When you see him running and fighting, it spreads to everyone."
Argentina face Cape Verde in the last 16 after the African nation surprised many by drawing with both Spain and Uruguay during the group stage.
Martínez warned against underestimating their opponents.
"It will be a very tough match. They have a very intense team, quick players and they defend well in blocks. But we have to focus on our strengths, stay concentrated and win.
"We have to stay calm and humble, knowing there will be moments when they have the ball. When we get our chances, we have to score, and then defend the way we always do."
Having only recently completed his long road back from serious injury, Martínez now finds himself at the heart of Argentina's defence again.
His latest comments make clear that neither his mindset nor his commitment has changed along the way.