Jennifer Welter remembers the exact moment she felt truly accepted as the first female coach in the NFL. It was back in July 2015, and she was training a rookie player with the Arizona Cardinals when the team’s linebacker Lorenzo Alexander strolled by.

“I was working [with the rookie] on some specialty, but he couldn’t resist asking the legend if there was anything he should do differently,” Welter tells The Post.

“Lorenzo replied: ‘You know what you need to do? You need to listen to the coach right there, because what she’s telling you is exactly right.’”

It was the validation the now-39-year-old needed, setting the tone for her history-making stint coaching inside linebackers under the supervision of the Cardinals’ head coach Bruce Arians.

“Lorenzo was very subtle, but he recognized me as the expert,” says Welter.

Two years on, the 5-foot-2, 130-pound trailblazer has written her first book: “Play Big: Lessons in Being Limitless From the First Woman To Coach in the NFL” (Seal Press, out now). Part memoir, part motivational guide, it reveals how Welter helped break the glass ceiling for sportswomen in the über-male-dominated field.

“My goal going in was very simple,” says Welter, who earned a doctorate in psychology four years ago. “It was being first, but not the last.”

It wasn’t easy to get there.

For 14 grueling years beginning in 2001, Welter played in underfunded women’s professional and semiprofessional football teams, including the Dallas Diamonds and Dallas Dragons. Remarkably, she never received more than $12 in cash per season — compared to the current base salary of $465K per season for first-year NFL players — and had to support herself by running a gym and supervising exercise classes.

Then, in 2008, Welter walked away from an emotionally abusive six-year relationship with her fiancé, giving up her house and living in her car for four months.

‘I would step on the field and be magic. I could do anything, I had no limitations. I could quite literally tackle anything.’

“It taught me a lot,” says Welter, who would sleep overnight in parking lots and shower at the gym she ran while also playing football. “Nothing I did in the relationship was good enough, nothing I did was ever right. I finally realized that I deserved better.”

The athlete eventually found a new apartment, but credits football with “saving” her life.

“It was the one place in the world where I could do great things,” says Welter. “Things had been bad at home but I would step on the field and be magic. I could do anything, I had no limitations. I could quite literally tackle anything.”

In 2010 and 2013, she was a member of the gold medal-winning Team USA at the International Federation of American Football’s Women’s World Championships, held, respectively, in Sweden and Finland. In 2014, she became the first woman to play on a men’s professional team, joining the Indoor Football League’s Texas Revolution as a running back.

In her book, Welter describes how she adopted the persona of “Gridiron Girl” to help her deal with the brutality on the field — “tough as nails … Beauty, brains and a beast on the football field.”

As far as male chauvinism is concerned, Welter claims she never experienced it in either the IFL or NFL.

“I just always assumed they were going to be great with me, and they were. I could have come in with a chip on my shoulder, saying, ‘You have to listen to me because I’m a woman,’ but I didn’t.

“Instead, I humbly listened to gauge how I could help them the most. I was able to bring a doctorate in psychology into the picture, so I just assumed there was always something I could add.”

Now, no longer aligned with a team, Welter conducts football training camps for women and girls throughout the US, and delivers motivational speeches.

“The door is now open for other women to go through and for little girls to grow up knowing what they are capable of,” says Welter proudly.

In 2015, the same year that Welter joined the Cardinals, Sarah Thomas became the NFL’s first female referee. Then, in January 2016, Kathryn Smith was hired by the Buffalo Bills as a special teams quality control coach.

“For me to be a role model is the coolest thing I can do,” says Welter. “I want the world to see things the way I do now — less about limitations and more about possibilities.”