'Do not let anyone make you see limits in life:' Q&A with the 1st female NFL coach

— -- Jen Welter, who made NFL history in 2015 when she became the league's first female coach, answered questions about what it was like to break the glass ceiling in a male-dominated sport, saying she would tell her younger self to "not let anyone make you see limits in life."

"It was a sport I had loved my whole life," Welter, a former coach of the Arizona Cardinals, said of football on "Good Morning America" today. "But I didn't have the opportunity to play, so when I made that first team, the promise I made is that I would step up to every challenge, no matter what it was."

Welter who has written about her experiences in her new memoir, "Play Big: Lessons in Being Limitless From the First Woman to Coach in the NFL," opens up about how she got into football and shares some of her top advice for girls in sports in an interview with ABC News.

Why or how you chose football over other sports?
Growing up in a small town in Florida, everyone was obsessed with football, including me. I loved the game but never thought of it as something I could do myself. In college, I found rugby. I loved it, and I was pretty good. Through rugby friends, I started playing flag football on the weekends and I got a call to try out for the Mass Mutiny women’s team. I quit my job to train full-time for the tryouts; put all of my stuff in storage, moved out of my apartment. I made the team and I was hooked. There was no turning back from that point.

What is the most surprising thing you’ve learned during your time in the NFL?
Just how mental the game really is at that level. I know it might sound funny coming from someone who has a Ph.D., because trust me, I can get mental. However, the truth is at that level, all the players are physically capable of succeeding. The differentiation comes through their football IQ, practice and study mentality, and their mindsets. Most people envision football training to be all physical practice. However, practice times are actually regulated by the league and the majority of the day is spent in the film room. Football truly is full contact chess.

What is your pep talk to players, and to yourself?
The greatest gift a coach can give a player is to make him or her better, in the game on the field and the game of life. And to truly help someone, you have to know him or her, as a player and a person, then you tap into that personal quest for greatness, within the collective goal. For myself, when I am scared and in doubt, I remind myself that I am playing for something bigger than myself. We generally say, football, family, and faith all those things are bigger than any one individual.

What advice would you give to your 13-year-old self?
Keep your wings, and do not let anyone make you see limits in life. My first love was tennis, and I was training to go pro. But I’m only 5-foot-2, and my coach told me I’d never be at the top of the game. Hearing that I could never be at the top just killed the fire in me, and I didn’t want to play anymore. So I’d tell myself: Don’t give up. That coach didn’t know what I was capable of. My size might’ve put me at a disadvantage, might’ve meant I had to work harder. But there was no way he could say for sure that I’d never be at the top of the game. I’m sure he would’ve said that I could never coach in the NFL, too! No one should have the power to steal your dreams.

What’s your advice to girls in sports?
Play your heart out. Enjoy every minute and compete to your greatest potential. Play as hard as you can. If you’re playing against boys, try not to take the trash talk personally. A boy is going to be upset if he gets tackled by a girl, or dunked on, or whatever. It’s not your problem. Go out there and show everyone what you can do, but most of all, play for yourself. Don’t worry too much about what opportunities you might or might not have in the future. Opportunities that you never could imagine might present themselves. They did for me. And if you can, try to get your parents to take you to women’s sporting events -- and bring your brothers. The games are great, you’ll be totally pumped, and you’ll be helping grown women like me get paid to compete in the sports we love, just like professional male athletes do. Then when you get older and want to go pro, young women will do the same for you.