It has been 40 years since the passage of Title IX -- a law best known for opening opportunities for females to play sports throughout their academic careers. When it passed in 1972, fewer than 300,000 girls played high school sports in the U.S. Last year, more than 3 million did.
Billie Jean King, 68, tennis star and women's advocate, has long supported the legislation. A year after it passed, she trounced Bobby Riggs in a tennis match on national television, aware that millions of eyes were on her.
"I just had to play," King told Newsweek not long after the match. She said she "wanted to change the hearts and minds of people to match the legislation."
We caught up with King on the 40th birthday of Title IX, getting her thoughts on female athletes, women's history and how she stays active as she ages. Here's what she had to say:
On women needing to understand where they came from:
I think the more you know about history, the more you know about yourself.
It's important to understand the fight that so many people had to [go through] for all of us. And young women need to understand that we're still not there. Even in the U.S., we're still only making 77 cents on the dollar … and it's absolutely ridiculous.
On the lack of opportunities in women's sports:
We don't have the professional leagues. We don't have anything compared to the guys. We don't get the support from women -- they don't buy season tickets. Guys buy tickets and worry about who is going to the game later; they understand it's about writing checks and supporting the community. Women's sports are a microcosm of society, and women need to support women.
On the women she'll be watching this Olympics:
I like [Allyson Felix] the track star. I'm fascinated by her. But personally, I'm always more concerned about how many professional opportunities they have once the Olympics are over.
On keeping active after years of knee pain (King recently had knee replacement surgery that she believes will be her last):
Two years ago, I'd had it. My whole world had really closed in on me. It got to the point where I couldn't walk a block -- I took a taxi to the gym, which is two-and-a-half blocks away.
Now I go to the gym. I play tennis again. I always say I expect this thing to outlive me
On working out at 68:
"I do at least 30 minutes on the bike, and I do sprints on the bike, too. I lift weights. But it's whatever works for you and gets it done. It's what works for you in your daily life."
On her life's true passion:
I can't tell you how much I love tennis. I love to hit a tennis ball. Some people can run all day, but that's not who I am … I love to hit the ball. I just love it. It's the best way for me to exercise. Every time I walk on the court, I know it's a blessing.
On women's equity in sports:
We're celebrating 40 years of Title IX, and I do think it's important that young women know [what it did].
Every generation passes the baton down. Now, it's your turn.
This conversation has been edited and condensed.
HuffPost Lifestyle is a daily newsletter that will make you happier and healthier — one email at a time. Learn more