I had set my mind on winning the 1500-meter gold medal in Helsinki in 1952. ... And, it all came disastrously wrong when I came fourth instead of winning. ... Instead of retiring in order to devote myself to medicine, I decided to go on for another two years while I was still a student, working clinically in London, and I did that.

Yeah. It’s a grandiose reaction. You are claiming you could really control this, but you failed.

The Berlin Wall limited my opportunities. It quite literally stood in my way. However, there was one thing which this wall couldn't do through all those years: It couldn't impose limits on my inner thoughts, my personality, my imagination, my dreams and desires.

My contemporaries were more upset about the Nobel than I was not to be recognised. One of them labelled it the 'No-Bell' prize! But it was fine by me. There's no Nobel Prize in astronomy and I was really proud that it was my stars that had convinced the prize committee that there was good physics in astrophysics.

After four knee surgeries and hundreds of shots injected into my knee weekly to alleviate swelling and pain, my body is begging me to stop the pounding. My previous three surgeries were on my right knee. My most recent knee surgery took place this July and was on my left knee.

The task of finally making a decision to hang up my racquet felt a lot more difficult than winning seven matches in a row in the Australian heat. It took me several agonizing months to finally come to the decision that my chronic injuries will never again let me be the tennis player that I can be. Walking away from the sport, effective immediately, is the right decision for me and my family.