As far as golf is concerned Harrington has seen and done it all, but at the age of 41 he still loves the game as much as he did when he started out as a rookie professional in 1995.
"I have conversations with a lot of sports people and if I talk to a soccer player and he tells me he's 32 and he's retiring I scream at him," the triple major champion said.
"Whether I scream at himself physically or I'm screaming inside my head, I'm saying 'Don't do it!'
"I'm not a guy who can just say no. You are retired for a long time and I tell you what, I'll still be playing competitive golf when I'm 70."
The Irishman captured the British Open title in 2007 and 2008, the US PGA Championship in 2008 and featured in six European Ryder Cup teams from 1999-2010, winning the biennial event four times.
Has his enthusiasm and desire dipped after all these years travelling the globe in pursuit of golfing glory? Not a bit of it.
"I love playing, I'm fascinated by the game," said Harrington after signing a new multi-year deal with his club manufacturers Wilson Golf.
"I have a young attitude, I'm physically stronger than I've ever been and I just love it, love it.
"Regardless of what anybody else thinks, I've got to think the best is yet to come - that's what keeps me going, that's what gets me up in the morning."
Harrington won the elite four-man Grand Slam of Golf event in Bermuda in October to end a two-year victory drought but he is less than pleased with his lowly 59th position in the world rankings.
His last competitive outing was a joint ninth-place finish at the DP World Tour Championship in Dubai at the end of November and he cannot wait to return to the European Tour at the Volvo Golf Champions event in South Africa that starts on Thursday.
"Over the last five weeks you'd be hard pressed to find somebody who's done more time, more practice, more anything on their game than I have," he said.
"If anything I'm still trying to keep a balance on things. I might be doing too much practice, thinking about golf too much, playing too many tournaments.
"I love everything about golf and I'm fascinated by everything about it," said Harrington. "Logically I know this isn't going to happen but every day I'm hoping to find the secret to this game."
Widely recognised as one of the best in the world from six to eight feet range when he was in his pomp in 2007 and 2008, Harrington has been trying to unlock the secret of his recent poor form on the greens.
"I've been putting extra emphasis on my putting in the last five weeks," he explained. "It is normally one of the strongest parts of my game but it's been weak for the last two years and I've been trying to bring it back up to speed.
"Last year I hit the ball from tee to green better than I've ever hit it but I didn't hole the putts at the right time. If you look at any player playing well, I defy you to name anyone playing at the top of the game who is not holing their share of putts.
"Sometimes that's saving pars, sometimes that's even saving bogeys. Obviously you'll have the odd birdie putt here and there but it's the amount of momentum that a good putt can give to a round or if you miss, the lack of momentum it can cause," said Harrington.
"Last year there were lots of things that were really good about my game ... but after most of my rounds I felt I played better than my score suggested."