And like most nurses, I found myself running into certain frustrations. I started to look for ways to make a better argument, to advocate more convincingly for the people under my care. That led me to read up on civil law and produce a few research papers, and then I did a master’s degree in health science and also an MBA. All of that allowed me to see other sides of the problem. It also showed me how issues affecting nurses could be elevated by approaching ministers and other people in power with sound, evidence-based arguments.

We need to have mentors. I think I've always been pretty shameless about seeking out people much smarter and much more experienced than me from the very beginning. Michael Seibel and other people. And the more successful I got, the more leaders I started seeking out, whether it was investors, or Sheryl Sandberg at Facebook, or I got the opportunity to spend time with Warren Buffett and he became a close mentor of mine.

Of all the gifts that tennis has given me over the years, the greatest, without a doubt, has been the people I've met along the way: my friends, my competitors, and most of all the fans who give the sport its life.

And also I have to say this is also part of the reason why I approached Jennifer Doudna, also, you know, we were very much in line in the way to do very precise research. It was not … it was fast but precise, and deep. For this we recognised one another – we are the same type of scientist who, you know, want to see the details of the data.

So why do I talk about the benefits of failure? Simply because failure meant a stripping away of the inessential. I stopped pretending to myself that I was anything other than what I was, and began to direct all my energy into finishing the only work that mattered to me. Had I really succeeded at anything else, I might never have found the determination to succeed in the one arena I believed I truly belonged. I was set free, because my greatest fear had been realised, and I was still alive, and I still had a daughter whom I adored, and I had an old typewriter and a big idea. And so rock bottom became the solid foundation on which I rebuilt my life.

So given a Time Turner, I would tell my 21-year-old self that personal happiness lies in knowing that life is not a check-list of acquisition or achievement. Your qualifications, your CV, are not your life, though you will meet many people of my age and older who confuse the two. Life is difficult, and complicated, and beyond anyone’s total control, and the humility to know that will enable you to survive its vicissitudes.