Mark Webber admits he no longer has that burning desire to compete in Formula One, but says he is still "super respectful" about how he goes about his business.
The curtain will fall on the Australian's single-seater career at the end of this season after he announced earlier this year that he is moving to the World Endurance Championship with Porsche.
It has been a trying campaign for Webber as his team-mate Sebastian Vettel wrapped up the 2013 Championship on the back of 10 victories while Webber is fifth in the Drivers' standings with not a single win to his name.
The last four races in particular have been very frustrating as he retired in three of them, and the veteran concedes he is struggling to stay motivated.
"I think towards the end of your career, you probably find little things that convince yourself that you're not enjoying it as much as you were," he told Sky Sports News.
"You're not 22 anymore and that's obvious; I'm 37 and I've done over 215 races at the end of the year, so the juice goes out of the tank a little bit.
"But at the end of the day, I'm still super respectful of who I'm racing against and how I go about it. I'm still not blasé about competing at this level; I still respect it at this level. But there comes a time when you've got to get that decision right."
Webber came close to winning the World title three seasons ago, but he was pipped at the post by team-mate Vettel at the season-ending Abu Dhabi Grand Prix.
He added: "If I'd won the Championship in 2010, that might not have been the best decision, if I'd retired then. But it didn't happen."
Webber believes one of the reasons he has struggled in the past few years is down to the Pirelli tyres.
"Little did I know what we were in for, probably, with the switch in tyres from Bridgestone to Pirelli," Webber said. "That was another thing; it's up to the drivers to get your head around that and sort that out, but even within the same tyre family - you can see it now with [Lotus team-mates] Kimi [Raikkonen] and [Romain] Grosjean - when you have these slight changes in tyres and how they can really affect the drivers' performance.
"That's been magnified on the Pirellis quite a bit in my opinion, through different driving styles and techniques and things like that.
"That hasn't helped I don't think - the top-flight edge of getting the most out of yourself week in, week out."
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