The world number one made the uncharacteristically downbeat assessment of his hopes ahead of the Farmers Insurance Open at Torrey Pines - the site of his last Major championship victory, when he won the 2008 US Open at the San Diego venue.
The 38-year-old Woods has had a string of near-misses since the play-off win against Rocco Mediate that year, racking up nine top-six finishes - including four in the Masters.
And he has now acknowledged that time is running out for him to take his current tally of 14 Majors past Nicklaus's record of 18.
"Every year that I get a chance to compete and play in tournaments and Major championships for as long as I decide to do it, every year counts," Woods said.
"Looking back from the beginning of my career to now, I know that I don't have 20 years in my prime. I don't see being 58 and being in my prime.
"Most guys don't dunk from the foul line at age 58, so it's a little different. But the outlook is still the same. I still prepare the same. I still work my tail off to be ready to compete at this level and beat everyone that I'm playing against."
Woods admitted that his constant golf since the age of three has taken a physical toll on him.
"I'm still able to generate the same amount of clubhead speed as I did when I was younger, it's just that I can't do it every shot anymore," Woods explained.
"I don't have the rotational speed that I used to and that's a fact of ageing."
Woods believes that his experience will still be enough for him to beat new generation of players, many of whom - such as Rory McIlroy - are well over a decade his junior.
And he is taking his inspiration from another American sporting great.
"When you look at Michael Jordan, when he first came out he was able to dunk over everybody, but he got beat up by the Pistons in three straight play-offs," he said.
"Next thing you know he built up his body and developed a fadeaway. So you do it a different way. You evolve as you age and I think I have done that so far."