Image copyright Getty Images

Kimiko Date, one of this year's BBC 100 Women, was the first Asian female tennis player to be ranked in the world's top 10. But arguably her biggest achievement was to come out of retirement at the age of 37 to enjoy a 10-year swansong that only ended in September.

She was called the crown jewel of tennis in Japan and reached a career-high ranking of world number four in 1995. So when Kimiko Date announced her retirement just one year later it was a big shock.

"I started to dislike tennis as I got close to getting into the world's top 10," she told me.

"Up until then, one victory had been enough to erase all the memories of hard work because it brought me a sense of achievement."

But then winning became the expectation.

"For example, I expected myself to get to the second week of the Grand Slams and the media expected it too. So if I lost, it was treated as a big issue. I became sensitive," she recalled.

The media's attention was intense because she was the only one of very few Japanese athletes competing abroad at the time. The only other high-profile Japanese player on the world sports circuit was baseball player Hideo Nomo, and he relocated to the US in 1995.

"Tennis was seen as a Western sport so people didn't think Asian players could win. There were no Chinese players like today," Date said.

"I also noticed by looking at other players that you have to make a lot of sacrifices to get to the top and I wasn't sure if I was able to. It was mentally exhausting."

Image copyright Al Bello/ALL SPORT Image caption Date shortly before her first retirement

"It was no longer the sport that I loved - and enjoyed hitting the ball endlessly as a child," she added.

After her first retirement at 25, Date was enjoying her life and marriage. But 12 years later, she decided to make a comeback.

"When I first retired, I hated tennis. I wanted to be as far away from the sport as possible. But then I started to watch tennis as a commentator. That's when I realised my renewed love for tennis and I noticed myself wanting to play again," she said.

But she was competing against players who were 10 years younger.

"My eyes couldn't follow the ball because of the gap in my career as well as my age," she confessed.

She also suffered some injuries, but she kept going, breaking some of the "oldest player" records. She is still the second-oldest winner of a World Tennis Association (WTA) title, in 2009, before reaching number 46 in the rankings in 2010.

I asked her whether she ever felt that she had reached her physical limit.

"My limit… I probably reached it many times. But if I decided that it was my limit, it would then become my limit. So I didn't. I kept pushing myself because otherwise there was no way I could compete against younger players."

Her story was held up as a beacon of hope to both men and women in their 40s that age shouldn't restrict what they can achieve.

For Date, tennis was enjoyable again as she no longer felt the pressure to produce good results.

Image copyright AFP

"Everything was fun. Practice was fun, training was fun, going on a tour was fun," she said.

"I couldn't believe how different I became. It was the complete opposite of who I once was, even though it's still me, playing the same sport."

But at home, she was facing another battle.

"I always wanted to have kids," she told me.

In fact she wanted to become a stay-at-home-mum just like her own mother.

"Even when I started playing tennis professionally, I thought I'd play for several years and after that, I'd get married and become a housewife."

But despite undergoing fertility treatment, she and her now ex-husband were unable to conceive. It was a very different type of challenge.

Image copyright Getty Images Image caption "I always say that the tennis court is like a life," says Date.

In tennis, she said, if you work hard, there will be results. Even if you fail, you can learn from your failings and that can lead to future success. But trying for a child wasn't like that.

"When I made a comeback, I knew I would have less of a chance of having a child because if my focus on tennis became greater, I would be able to focus on fertility treatment less. I wanted to play tennis but I also wanted to have kids. That became my dilemma and it was very stressful," she said.

"Even now, as a woman, even though my chance is extremely small, it would be a lie if I said I've totally given up having kids."

But as an athlete, she feels blessed.

"In my first career, I did my best by reaching the world's number four and experiencing the semi-final of a Grand Slam. But then to be in the top 50 in my late 30s was something very special.

"I always say that the tennis court is like a life. You experience happiness, conflict, highs, lows, and are forced to make decisions. For me to be able to enjoy it a second time, I know that experience is irreplaceable. I thank tennis and my supporters and I feel proud of myself."

When she announced her final retirement last month many Japanese players expressed their gratitude for her as a role model. Japanese sportsmen and women are a far more common sight on the world stage these days and the length of her career has also proved inspirational.

Japanese international footballer Shinji Kagawa tweeted: "She taught us that age isn't a handicap, it's an advantage of more experience."