"It's been seven months since I last played and I will need some time to find my rhythm, find my game and come back to the top," the Belgian told a news conference on Tuesday.
"It's about doing things step-by-step. I have to accept that I'm not going to be able to play my game straight away. If I win, if I lose, whether I play well or not, it really doesn't matter to me. I'm playing and that's the most important thing."
The former world number one has not played since the U.S. Open and spent much of the last 12 months recovering from the debilitating virus mono-nucleosis.
Henin felt well enough to begin playing again in January, only to suffer a knee injury preparing for the Australian Open.
"It's been very difficult," said the 22-year-old, who won the French Open and U.S. Open in 2003 and last year's Australian Open before illness ended her dominance of the game.
"It was a big frustration because I had worked very hard to get back, but maybe I just wasn't physically ready to play in Australia."
Henin was first struck down by the virus this time last year and says there were days when she did not feel well enough to get out of bed.
"I think the only people who can understand that are the people who have been through it," she said. "One day I would feel okay; the next I would feel really bad.
"There were days when I just couldn't wake up and when you are used to being at the top and used to competing every day, that's very hard to accept.
"I tried to stay positive but there were times when I felt very low.
"I didn't miss things off the court so much, like the travelling, but I did miss being on the court and fighting. I missed winning."
FRENCH OPEN
After being diagnosed with the virus 12 months ago, Henin-Hardenne attempted to defend her French Open title but lost in the second round.
She did not return to competition until the Olympics in August, when she surprised herself by winning the gold medal.
"I still don't understand how I did that because I wasn't feeling 100 percent," she said. "But the atmosphere was amazing and I pushed my limits."
Henin, who has slipped to 40th in the world rankings, played down her chances of emulating her compatriot Kim Clijsters, who won the Pacific Life Open title at the weekend in only her second tournament back after missing much of last season with a wrist injury.
"Kim is Kim and I am Justine Henin," Henin said. "What Kim did was great but dealing with an injury and dealing with an illness are different things."
Henin has spent the last two weeks at her training base in Saddlebrook, Florida with her fitness coach Pat Etcheberry and should be used to Miami's warm, humid conditions.
She is seeded 19th in the Nasdaq-100 Open draw and, after a first-round bye, will play Australian Samantha Stosur or American Abigail Spears in the second round.
"2005 is going to be a year of transition for me," Henin said. "I'll have to come back to the top and I'll have to find my level again. I need to get back all the feelings I had when I was at my best."
