Two weeks ago, Pierre Rouzier was putting something in his car at his home in Amherst when he heard a truck hit a bump in the road, causing a loud clatter of metal to startle him.

The sudden, alarming sound forced Rouzier to immediately turn and crouch. “Where is it?” he impulsively thought to himself. “Where do I have to go?”

Last June, every time his wife dragged him out shopping to a department store, Rouzier would venture off to the men’s belt section. He’d look for a webbed belt with a two-ring buckle that he could stitch across.

In his own words, he was looking for a belt that could be used as the perfect tourniquet.

“I was on a mission,” Rouzier said. “I was like, ‘I’m going to find the right belt.’”

A lot has changed in the year that’s passed since last April’s Boston Marathon bombings. One thing that hasn’t changed, though, is Rouzier’s passion to help others.

That’s why he immediately jumped to attention when that truck made a loud sound near his home as he instinctively wondered how he could help. That’s why he shopped for that belt and why he even bought a pair of cargo pants with bigger pockets so he can stash more things.

And that’s why he’ll return to the Boston Marathon this Monday, to the very location where just over a year ago, thousands of lives were impacted and a city was shaken as a result of two bombs that exploded near the finish line, which killed three people and injured more than 200 others.

Rouzier, a University of Massachusetts staff physician, was at ground zero of the attack, where for the fifth year in a row he was stationed at a medical tent less than 100 yards away from the race’s finish line to work as one of many volunteer triage doctors.

Most racegoers who arrive to the tent come experiencing dehydration or related symptoms as a result of running 26.2 miles in the heat. But at 2:49 p.m. on that fateful day, a bomb exploded in the middle of a crowd of spectators watching the race on Boylston Street. Moments later, another bomb went off.

As much of the crowd hurriedly dispersed in fear of their lives, Rouzier, as if it was a reflex, rushed into the chaos – facing pools of blood, torn-off limbs and sheer panic – as he tried to save as many lives as he could.

Rouzier’s brave response didn’t surprise many, especially his son Anthony.

Anthony was giving an accounting presentation for his MBA class in Florida when he received a text from his dad: “Bombs going off at the finish line. Say your prayers!” the text read.

Moments later, Anthony went online to find out what was going on and stepped outside of class to try to get in touch with his dad. But it wasn’t until two hours later – several texts having gone unanswered – that Anthony finally heard back.

“I’m OK, I’m going to go find more people,” his dad said. “Hopefully another bomb doesn’t go off.”

“It was no surprise to me that he would do that because that’s just the way he is,” Anthony said. “He doesn’t think twice about helping people because that’s just what he knows.

“At a time like that, my natural reaction was really just how appreciative I was to have him in my life and if the worst thing were to happen that he did it because he cared about people, and that’s just the way he is.”

One year later, nothing has changed.

Rouzier will be back on Boylston Street on Monday for his sixth consecutive Boston Marathon as a volunteer triage doctor, doing what he loves most: helping others.

It’s a state of mind that has fueled him for over three decades of medical work, 17 years of which he’s been at UMass for. Facing such a traumatic experience such as last year’s bombings may deter some from coming back, but not Rouzier.

“It’s been on my calendar of something that’s important to do for the whole time (since the bombings),” Rouzier said.

There’s almost never a day that goes by when Rouzier doesn’t think about what happened a year ago. Especially, recently, he’s given countless interviews recalling the day that he – and everyone associated with it – will remember forever.

He said he cries often as he comes to grips with the emotional toll of that day and the aftermath.

He’s also gained a stronger appreciation of life – one that no doubt existed before last year’s tragedy, but one that also grew as a result of it.

“I’ve always been an optimist,” Rouzier said. “I say prayers and thanks every day I’m alive. When I see somebody who’s an amputee, I’m just kind of drawn to them, just to wonder what their story is. Wondering how they got hurt and what their challenges are. It’s really made me appreciative of life.

“I was always that kind of person, but it made me even more (like that).”

Most of all, though, what keeps driving Rouzier back – and ultimately back to this year’s Boston Marathon – is his love for people.

It’s why one of the main things he’s looking forward to on Monday is reconnecting with people he hasn’t seen since last year’s marathon, a connection that has become stronger this year more than any other year in light of last year’s events.

“The emotional charge of it all will make it a little different,” Rouzier said. “You always like to see people you haven’t seen in a long time. I’ll see a lot of people I haven’t seen in a year. So that will be a big emotional incentive, just seeing people. A special thing happened. You shared that special bond of being there.”

More than that, though, his love for people will drive him to do what he does best on Monday: help people when they need it. Belt-turned-tourniquet in tow – just in case – Rouzier will be more prepared for what’s to come than ever before, and he wouldn’t have it any other way.

As his son Anthony said, it’s just what he does.

“He loves doing it,” Anthony said. “He’s there at the triage tent and he loves to be in the thick of that. So for him to go back, that’s a type of closure to make a statement to himself that ‘this is something that I’ve done forever and I will continue to do it because I love doing it. And I’m not going to be deterred from what I love to do by some kind of cowardly act.’ He’s one of the people that embodies that more than anyone.”

Stephen Hewitt can be reached at [email protected] and followed on Twitter @steve_hewitt.