The 36-year-old Dubliner is refusing to rest on his laurels after becoming the first Irishman to win the Open in 60 years after edging out Sergio Garcia in a four-hole play-off last July.
Harrington is in the Middle East for the Abu Dhabi Golf Championship alongside defending champion Paul Casey, Ian Poulter and Luke Donald.
“I don’t think anything is truly surprising about being a major champion. The most interesting thing is I’ve reset myself back to maybe my early years on tour where I want to work harder and harder,” said Harrington.
“I’ve actually gone back to being a bit obsessive about the fact that I’m getting out there and working and practising. It’s like I’ve got to go prove something all over again. It’s neither a good or bad thing. You have to have a good balance; that’s always an area that’s an issue for me, in that I would have a tendency to overdo things rather than to get the balance right.
“I was getting the balance right going into the Open. It’s not that I am getting the balance right now; it’s just that I have to work hard and make sure that I don’t overdo it.”
Harrington has pulled out of next week’s the Buick Invitational in San Diego on the PGA Tour after a bout of illness over the Christmas period disrupted his pre-season preparations.
The world number nine is eager to get the new year underway at the Abu Dhabi Golf club tomorrow.
“I am definitely looking forward to getting back out on to the golf course,” added Harrington, who finished in a tie for fifth in Abu Dhabi last year. “I still have got a little element of what I’m working on and still just getting my game worked through.”