Mark Webber conceded on Thursday afternoon that the march of time combined with impending rule changes in Formula One for next season had been major factors in his decision to quit and switch to sportscar racing with Porsche.
The Australian Red Bull driver, who will be 37 in August, said no single reason had persuaded him to quit, but a mixture of factors.
He said: "There's lot of reasons that come into the pot when any sportsman or woman comes to that time in their career when they want to call it a day. That's another small ingredient.
"There's going to be big, big changes in the sport next year.
"So let's see how the category is next year in Formula One. I'll be interested to watch every now and then and watch these guys do their stuff."
Webber denied that the fact that Porsche were first to announce his 2014 plans, rather than Red Bull, was in any way a dig at his current team.
He added, simply, that "it was about Porsche and Mark Webber today" and made clear that he had made his decision without being influenced by anything other than his own goals and ambitions.
He said he had been in touch with Red Bull owner Dietrich Mateschitz over his future for a number of months.
Talking to reporters at Silverstone, on the eve of opening practice for the British Grand Prix, he said: "I've helped the team today... They know they've got to make some decisions in the future."
He added that it all added up to "perfect timing" for him individually.
"The timing is perfect for me," he said. "I'm very, very excited about my new chapter and new challenge ahead. It's one of the most famous and most well-respected brands in automotive and motor racing in Porsche, so that's something that personally I'm very satisfied about taking on.
"The decision has been there for quite a long time for me actually, I've known for quite a while, and had a plan and stuck to it.
"But still I will be at this level and focusing on achieving very, very strong results in my last season in Formula One"
The veteran of 203 Grands Prix turns 37 in August.
He is already the oldest driver on the grid this season by four years following the retirements of German Michael Schumacher and Spaniard Pedro de la Rosa last year.
He said that Red Bull owner Mateschitz had supported him.
"Dietrich has been completely up to speed with my thinking in the last six to eight months, so Dietrich has been absolutely on-board and on-message about with where I've been at," he explained.
"He certainly encouraged me not to rush my decision when I approached him earlier in the season and, basically, all of the right channels and avenues that we went through to get the message across, as subtly as we could in terms of the announcement... it was done in the right way."
He suggested on his website that he was not severing links with the energy drinks completely, adding "going forward I will remain tightly inside the Red Bull family, working with the brand."
He said that he intended to race as hard as ever in the final 12 races of his F1 career.
"Going forward for the rest of the season it doesn't change a huge amount because I've known the decision," he said. "Nothing changes from my approach now because now it's out for everybody,, but the last few races obviously I want to be challenging for the top steps and when you get everything right you want to get wins as well.
"So I don't see that being a huge, huge difference. It's in my interests to keep my motivation up until Brazil and work hard with the guys - that's important.
"At this level the effort to get the car out there, I'm fully respectful of that, so I need to keep pushing for both myself and the team. They obviously put a lot of work in."