Rafael Nadal is not thinking about retirement as he plans to play as long as his body allows him to compete at the highest level.
Nadal was always pretty clear in the way he sees his future and it was always tied to his body being able to cope with the load. If he's able to play and be competitive in events, he'll continue to play and when that becomes impossible he'll stop.
He reitarated that ahead of the ATP Finals saying:
"I'm happy playing tennis. I still keep the love for the sport, the passion. If my body allows it, I will continue to enjoy my day-to-day career as a professional tennis player. When that's no longer possible, it's time to think about other things. For now, I still feel satisfaction and passion for tennis."
Speaking further he explained how every trophy you win is different:
"Each title is different, each moment you enjoy in a particular way. This year, I experienced exciting moments in winning the Australian Open and at Roland Garros. It was a very good year, but difficult at the same time, as I had physical problems. But, if I put all this into context, it was an unforgettable year. I reached 22 Grand Slam titles at Roland Garros, an unforgettable moment for me, due to all the issues surrounding the tournament."