Alonso returned to F1 with Alpine in 2021 after taking a two-year break to race in the FIA World Endurance Championship, the Indy 500 and the Dakar Rally.
Alonso's third stint at the Enstone outfit got off to a slow start but once he got back up to speed the Spaniard re-found his old form, frequently suggesting he was driving at his best-ever level in 2022, a season which was blighted by reliability issues.
For 2023, Alonso jumped ship to Aston Martin, which struggled last year to finish seventh in the constructors' championship.
While the team is a step down from Alpine in the short term, the Lawrence Stroll-led outfit managed to convince Alonso with its long-term project, answering to Alonso's desire to stay in F1 for years to come.
And the 41-year-old says he wouldn't have accepted to continue if he didn't think he was still capable of performing at his peak, or if he wasn't convinced that Aston can close the gap while he is still around.
"No, I think I will not accept that and I will not continue if I don't believe that we can have a chance," Alonso said.
"I don't know if it's one percent chance or 10 percent, but I will only continue because I believe that we will have a chance.
"Next year to close the gap that Aston Martin has I think it's unrealistic, but we need to put the foundation we need, to put the baseline to future cars and to work better than the people around us.
"This is a very competitive environment, so to become a champion you need to deliver something special. I'm ready to deliver something special from my side and I expect the same from the team."
Alonso, who penned a multi-year deal at Aston last summer to replace the retiring Sebastian Vettel, added he would stay in F1 "for two or three years for sure", but wouldn't be drawn on predicting exactly how much longer he aims to drive after that.
"I think I would take it year by year," he explained.
"I don't know, [in 2021] I was maybe not 100%. If I do a few seasons like that, even if I perform from the outside okay but I don't feel happy with myself, then maybe I stop.
"And [2022] for example, I feel very proud. I will continue whatever the results are next year, because I know what I can give to the team. So, I don't know, two to three years for sure.
When asked to expand on what he can bring to Aston Martin's rebuild, he said: "Where I believe I can make a difference is when it comes to crucial moments in the races, experience, decisions or thinking about the strategy.
"It's not about the driving abilities, I think we all have high talent, driving cars fast. It is more about the head and how you control a few things."
