Fernando Alonso has admitted that he is more likely to quit Formula 1 as a result of the demanding schedule rather than any decline he may experience now he is 42 years old.
The Spaniard has just enjoyed one of his best seasons in the sport after 21 seasons, and shows no signs of slowing down.
Eight podiums, including some impressive drives in Monaco and Canada, were highlights of his season before the Silverstone based outfit failed to follow a successful upgrade path.
Now entering his 22nd season in the sport, he is worried about the impact that 24-race calendars could have on both his mind and body.
Alonso: These kinds of things will drain my battery
"I said many times even before 2018, the day that I will stop racing is not because I feel not motivated for driving or I feel slow,” he told Motorsport.com.
"If I feel slow one day, I think it will be noticeable and think I will not be happy with my performance and I will be the first one to raise my hand and say 'this is time [to stop]'.
"But, I don't think that time will arrive. Honestly, in terms of feeling slow, because I have extreme self-confidence in my performance, it could be that with the calendar and with the demanding schedule that one day I will feel it's time - because there are other things in life.
"It's been a very demanding season with only 22 races, with two cancellations. Next year with the proper [24-round] calendar, we have to see how it feels.
"I saw that it's a triple-header. I don't know why, I thought that Vegas was alone next year… It's three races together. These kinds of things will drain my battery, not driving."