Alonso walked away from F1 for two years at the end of 2018 after growing tired of media and commercial commitments while his McLaren team fell into the bottom half of the standings.
In his time away, he twice won the Le Mans 24 Hours, chalked the 2018-19 World Endurance title and contested the Indianapolis 500 before returning to F1 with Alpine in 2021.
Despite turning 42, a 2023 season at Aston Martin returned him to the podium eight times to boost his motivation further.
He said: "To be competitive, to feel the speed again, and to arrive to the weekend again knowing that you need to do everything perfect because there is a podium possibility or a race win possibility, that really gives you a very different approach and a very different love for the things you do and dedications."
But the two-time champion concedes that F1's punishing schedule could be the factor - rather than age leading to a decline - that prompts him to quit again.
Alonso reckoned: "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.
"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."
The 2023 term dropped to 22 rounds after the return of the Chinese Grand Prix was postponed another year because of the pandemic, while an Imola event was cancelled by severe flooding.
It ended with an Austin-Brazil-Mexico triple-header followed by the Las Vegas GP running back-to-back with the Abu Dhabi finale.
For next year, the provisional calendar features a season-ending Vegas-Qatar-Abu Dhabi triple-header. This is under review amid pressure from teams and drivers, who argue the timetable is too gruelling as illness swept through the paddock in the Middle East.
Alonso believes it will be this running order that determines when his love for F1 runs out, rather than any performance drop-off. He continued: "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."
