Tiger Woods is pain-free for the first time in two years but accepts he will never regain the game that saw him dominate golf for a decade.
The world number four returns for the first time since back surgery in April to play the US PGA Tour's National event at Congressional on Thursday.
The 38-year-old won the last of his 14 major titles at the US Open at Torrey Pines in 2008.
"The difference as I've aged is I can't play the way I used to," said Woods.
"But I'm pain-free. It's been a very long time, probably a good two years since I've felt this way."
Woods' dominance between 1997 and 2008 relied in part on the American's power game, but the current crop on the PGA Tour are now hitting it further - and Woods accepts he has to find other ways to win as he prepares to make his comeback from back surgery on 31 March.
"I feel old. The Chinese kid [14-year-old Guan Tianlang] who qualified for the Masters last year was born after I won the tournament for the first time and that is just not cool," the American told a news conference.
"That is what is coming. The next generation are taller, bigger and more physical - these kids in college, all the long-hitters are 6ft 2ins to 6ft 4ins.
"I was number two in driving distance for a number of years just behind John Daly - things have changed dramatically.
"I have to rely on different parts of my game like strategy and course management."
Woods is ahead of schedule for a playing return as he had initially targeted next month's Open Championship at Royal Liverpool, where he last lifted the Claret Jug in 2008.
But after a carefully managed programme of physiotherapy and dietary changes, he feels ready to come back earlier - although he admits had this week's Quicken Loans National Tournament not been an event that benefited the Tiger Woods Foundation he would not be playing.
The former world number one's injury problems began in 2008 when he had season-ending reconstructive surgery on the anterior cruciate ligament in his left knee immediately after winning the US Open.
He has had further problems with that knee and an Achilles tendon but the back injury proved to be the worst of all.
Woods added: "Anyone who has had any kind of nerve impingement knows it is no joke but that part was relieved as soon as I got out of surgery.
"I felt I had my life back. I was able to do things, normal activities I took for granted."