"The history of women's sport is a history lesson on resilience," says Olympic gold medalist and veteran wrestler Erica Wiebe. She's one of five phenomenal female athletes featured in new episodes of Inside an Athletes Head, now streaming on CBC Gem.

What motivates these athletes to keep going? To push through exhaustion and injury, as well as loneliness, frustration, and self-doubt. What makes a gold medalist want to try to do it again? How does a champion handle people telling her she's "too pretty to box?" How does a long distance runner balance motherhood and Olympic qualifying? Here's what these women have to say.

Jelena Mrdjenovich turned pro in 2003, and won her first title in 2005, but some people still don't believe she's a boxer. (Inside an Athletes Head/CBC)

People tell Jelena Mrdjenovich that she doesn't look like a fighter all the time.

"They're like, 'Seriously, why do you do this? You should get into modelling or something','" she says. "Then I say 'Well, thank you for the compliment, but what I do as an athlete shouldn't have anything to do with how I look... If you don't believe me, check out my highlight reel.' I send them to YouTube."

That highlight reel contains a string of knockouts that have made her the World Boxing Association and World Boxing Council female featherweight champion, and one of Canada's most decorated active boxers, man or woman. Which isn't bad for someone who first walked into a boxing gym just looking for a good workout. What hooked her, she says, was the mental challenge of the sport.

"Every time I went into the gym, I wanted to learn more, I wanted to do more, I wanted to feel more," she says. "You realize it's not just two knuckleheads beating each other up, it's a chess match. It's 'I'll show you a move and see what you do, and I'm gonna try to find a different way to react.'"

Watch Inside an Athlete's Head: Jelena Mrdjenovich (Boxing)

Erica Wiebe says one of her favourite things is giving seminars to young women wrestlers who 'don’t question their ability to be in the sport of wrestling.' (Inside an Athletes Head/CBC)

When Erica Wiebe started wrestling as a 13-year-old, women's wrestling still hadn't made its Olympic debut. Now, not only is it an Olympic sport, but Wiebe herself is an Olympic gold medalist. While the respect for women's wrestling still isn't "where we need to be," she says she is constantly impressed by the girls and young women following in her footsteps.

"It's really amazing to just travel across Canada, do clinics, and see this whole group of young women […] who look up to me, and don't question their ability to be in the sport of wrestling," she says.

Before she won gold at the 2016 Rio Olympics, Wiebe thought the hardest thing she could do in her sport was to go to Rio and be ready to compete on match day. Now, she has a different opinion.

"Now I think the hardest thing I've ever had to do was come back, and pursue doing it again," she says. "It's lonely, it's challenging, it's a whole new level of visibility and expectation and judgement. And in the midst of that, you just have to constantly remind yourself of who you are and what your values really are."

Watch Inside an Athlete's Head: Erica Wiebe (Wresting)

Krista DuChene started running marathons for fun. Now she's an Olympian. (Inside an Athletes Head/CBC)

Runner Krista DuChene had an unusual path to becoming an Olympian and Boston Marathon medallist. A former collegiate hockey player, she didn't start running seriously until she was already in her 30s and a mother.

"As I kept running, I started to get faster, and I started to work fewer hours as a dietician […] I started doing the math and saying 'Okay, just a little bit faster, increase my mileage a little bit more' and it grew."

DuChene says one of the keys to being a high-performance athlete while also being a parent is to "be really clear and concise about the job I was doing at the time."

"When I was out for a run, I was out to run, and not feeling like I should be with my babies," she says. "When I was with my kids, I was enjoying that, and not feeling like 'Oh, I should be running.'"

Watch Inside an Athlete's Head: Krista DuChene (Long-Distance Runnning)

As a teenager, Rugby gave Olivia Apps a new sense of confidence. (Inside an Athletes Head/CBC)

As a teenager, rugby became a source of confidence for Olivia Apps. Apps has alopecia universalis, a medical condition that causes total hair loss. That made adolescence, and the transition to high school, tough for Apps. But discovering her love, and gift, for rugby, helped her find a new self-confidence.

"My older sister played rugby and was like, 'You should give it a shot,'" she says. "I was like, 'OK, I guess I just run through people and score tries.' It seemed simple enough [...] And I knew if I could take on anything on the rugby field, I could take on anything in life."

At 5'5", Apps is one of the smaller women on Canada's Rugby Sevens team. In an interview with CBC Sports' "Bodies of Work", she said that while she doesn't fit the typical mold of a rugby player, she's learned how to find a niche on the field.

"In sevens, you need players of all sizes," she says. "A lot of my teams are stronger and bigger, and have those strengths, but I carry other strengths in terms of speed and agility."

Watch Inside an Athlete's Head: Olivia Apps (Rugby)

For Melissa Humana-Paredes, who's father coached the 1996 Canadian Olympic team, beach volleyball is a family tradition. (Inside an Athletes Head/CBC)

In her episode of Inside an Athlete's Head, Melissa Humana-Paredes says the expectations she places on herself. Like so many second-generation Canadians, she wants to prove that the sacrifices made by her parents — who came to Canada as refugees from Chile in the early '80s — were worth it.

Her father was also a volleyball star in Chile before leaving the country and he coached Canada to its only Olympic volleyball medal in 1996. Her dad was her first coach and is still the person she turns to when she's struggling.

"He kind of knows everything, and he has my best interests at heart," she says. "He's not gonna feed my ego and pat me on the back. He's gonna be able to give me critical feedback when I ask for it, or even when I don't ask for it."

She says that people not familiar with the sport might be surprised at how mentally taxing beach volleyball is.

"We aren't allowed substitutions, we aren't allowed coaches [on the sidelines]," she says. "You're out there on your own, just two of you […] having to deal with external elements — sand, sun, wind — trying to beat a team that knows your weaknesses, and you have to figure it out, and no one can help you with that except your partner."

Watch Inside an Athlete's Head: Melissa Humana-Paredes (Beach Volleyball)