Tiger Woods made himself unavailable for the US Ryder Cup team because he did not think he could win a point in the matches, the former world number one said.
The 38-year-old American was sidelined for three months after having back surgery in March.
His form this year would have left him relying on a wildcard pick from skipper Tom Watson for next month's matches against holders Europe at Gleneagles in Scotland and he pulled out of contention last week.
"I wouldn't be ready ... and I just couldn't help the team," Woods told Britain's Sky Sports television in an interview.
"When your name is called you have to be able to go out there and get a point and I just didn't feel I could be ready enough to get a point.
"It was time to shut it down, get stronger, get more explosive again and get back for next year."
World number 11 Woods missed the cut at the US PGA Championship this month, having made a late decision to play after pulling out of the WGC-Bridgestone Invitational the week before.
He is not planning to pick up his clubs for another month but will work in the gym as he builds towards a return at the World Challenge tournament in Florida in the first week of December, an event he hosts.