The recently turned 24-year-old linebacker is never going to forget cancer. That's impossible.
There's a titanium rod in his left leg as a constant reminder of the rare form of bone cancer that caused him to miss the 2009 season at Boston College. If that isn't enough, there are memories of the draining effects of chemotherapy and radiation, and those lingering doubts about life.
It's always there. Things like that never go away.
But Herzlich doesn't want the past to define his life. It's time to move on and play the game he loves, and Monday was the official first day of his NFL career.
"I want to go from being a feel-good story to making an impact on the field," said Herzlich, who talks about his fight with cancer without hesitation, while giving clear hints that he would rather be discussing football.
That's his life now, and that's his focus.
Still, Herzlich can't deny he has beaten the odds. The 2009 Atlantic Coast Conference defensive player of the year got back on the field last season with the Eagles, and he made the NFL despite being passed over in the draft.
The Giants signed him as a free agent and he impressed everyone in training camp and in four preseason games. The final step was surviving the cuts that reduced the Giants' roster to 53 players Saturday. He did that, too.
Herzlich spent Monday getting ready with his teammates for the season opener against the Redskins in Washington Sunday.
"I got through today, so that's one day," Herzlich said. "I don't think anyone tries to make the NFL for a day, so we'll see how the career goes."
The 6-foot-4, 246-pounder expects a lot out of himself. If he makes a bad play, he expects to be booed. He doesn't want anyone's sympathy.
"I expect them to be (angry) at me if I make a bad play," Herzlich said. "I'm (angry) at myself if I make a bad play.
"I don't think your story is ever over. When you talk about this story that's actually my life; yeah, it's a story, maybe the book is getting toward the end of the chapter. But that's my life and that's going to keep on going.
"Lots of changes are going to happen, whether as related to football or what," Herzlich added. "It's time to start a new chapter."
Herzlich doesn't know whether he will be active for Sunday's game on the 10th anniversary of the Sept. 11 terrorist attacks. If he does, his job will be on special teams, an area in which the Giants have struggled in recent years.
"I think we have a lot to prove. I think that that's what it is with the special teams," Herzlich said. "We want all three phases of the game to be the best that they can be. You said (the special teams play was) sporadic. You saw great things on film from our special teams and then you saw some things that didn't go our way a little bit. We need to shore that up."
While the workout on Monday was only a walkthrough, Herzlich noticed the intensity and speed had increased.
"I think this week it's all about business," he said.
This past weekend was more about waiting, hoping and eating to pass the time away. Herzlich and some fellow rookies -- safety Tyler Sash, linebacker Spencer Paysinger and fullback Henry Hynoski -- all went to breakfast at IHOP.
"We tried to get our minds off of it by gorging ourselves with pancakes," Herzlich said. "Then I went to Chili's and sat by myself for the afternoon watching the BC football game because I couldn't find it on TV anywhere else. So I just sat there by myself, tried to keep my mind off of it."
When Herzlich didn't get a telephone call from the coaching staff by 6 p.m., the deadline to make cut, he waited another three minutes and then tweeted to all his friends that he was still a Giant. He gave himself roughly 90 seconds to celebrate and enjoyed all the emails and tweets wishing him well.
"Then you realize anything can happen from now on," he said. "It's a great feeling to make it this far. I have to keep working and working and working and try to stay on the team."
Defensive captain Justin Tuck smiled when asked about Herzlich.
"It's very hard for me to say anything good about him because he went to BC," said Tuck, a former Notre Dame star. "But you always root for guys like that. He's accomplished so much with all the things he went through. I paid attention to him in college and hopes he returns to that form when he was at BC and help this football team out."
Guard Chris Snee, a former Boston College player, said Herzlich was someone who benefited playing in four preseason games instead of two, which some owners wanted in exchange for an 18-game regular season.
"Everyone knows what Mark has overcome," Snee said. "It just speaks for what type of guy he is and how strong he is."
Tackle Kareem McKenzie was impressed with how far Herzlich has come since being diagnosed.
"That's says a lot for anybody to take the worst of what life has to offer and to make the best of it and take advantage of the opportunities you are given," McKenzie said. "He definitely has a great work ethic and an unbelievable determination."