"Everyone works so hard on their game and on their body," said Isner. "Most of the time, it comes down to who is more relaxed mentally; on the court while playing and off the court. There is so much that goes in to being a good tennis player. It's not just what you can do well on the court, it's between the ears as well."
Isner is in a good place. He had an impressive 2018, highlighted by his fantastic feats in Miami, where he became the oldest masters champion in history, beating three top-10 players on the way. He also reached the last four at Wimbledon, losing 26-24 to Kevin Anderson in the fifth set of a six-and-a-half hour marathon, reached the quarter-finals of the US Open and claimed a title at Atlanta.
Isner, who turns 34 in April, is supposed to be in the twilight of his career but has no plans to retire.
"As long as I'm still enjoying it and still having fun competing, I want to be out here as long as I possibly can," said Isner. "As a tennis player, or any professional athlete, our career has a shelf life. I don't want to waste any opportunities, I don't want to look back on it when I'm 45 and think I could have done a lot more. I think I can play another three or four years ... and hopefully I can play some more after that."
At 2.08m, the imposing Isner doesn't have a typical tennis build. That brings obvious advantages - he served more than 1200 aces last year - but also challenges, especially with the stress on his body.
"Taking care of my body and my health is my full-time job," said Isner. "Everything I ever do is tailored around my body, to keep myself healthy [and] fit. This off-season, I have felt as good as I've ever felt."
Isner has a strong record at the ASB Classic, with two titles (2010 and 2014) and four other quarter-final appearances, and wants another Auckland run.
"I had a very good year [in 2018] but not a great start," said Isner. "That is a focus for this year, to start better. But we know how difficult the beginning of the year is and how good everyone is. Especially at this tournament, every year, it's so strong, and it's the same this year."
Monday's action at the ASB Classic is headlined by Canadian whiz kid Denis Shapovalov, who faces 2017 finalist Joao Sousa.
Auckland-raised Cameron Norrie is also in action, along with 2008 champion Philipp Kohlschreiber. The legendary Bryan brothers also feature today in the doubles field, as well as Kiwis Artem Sitak, Ajeet Rai and George Stoupe.
