In an interview with Reuters held after a World Cup super-giant slalom was cancelled in the resort of Val D'Isere, the skier also elaborated on her disclosure to American magazine People this week that she had suffered bouts of depression.
The American ended up in the safety netting in the downhill, a discipline in which she is world and Olympic champion, on Friday for the first time since 2007.
"Things are a little bit tough," said Vonn. "I started the season well ... now I'm definitely feeling like the energy isn't there.
"It's becoming more and more difficult to ski the way I want to. With yesterday's crash and my near-crash in the training run, I'm losing self confidence," added the second most successful female skier of all-time ahead of Sunday's giant slalom in Courchevel, France.
Vonn began the season by controversially stating her desire to race against the men in Lake Louise, Alberta, and then spent a period in hospital with stomach problems.
The 28-year-old is now facing mounting opposition from Slovenia's Tina Maze and feeling the strain of competing in all five alpine skiing specialities.
Sunday's giant slalom could be her last race of the year before she returns home to the U.S. for Christmas.
"My energy is not currently where it used to be," said Vonn. "Since being sick I have definitely struggled a lot and people are thinking my skiing it's not where it should be.
"I'll think hard after tomorrow's race about what my goals are. I think at this point that fighting in the technical events isn't really a realistic goal," she added referring to the slaloms and giant slaloms.
"I need to accept that and find a solution."
Vonn, who has won several races this season, is undecided about which world championship events she will compete in at Schladming, Austria in February.
"I don't think I won't race at the world championships, they are still two months away, but it's realistic that I won't be racing in a few technical races coming up," she said.
On her recent magazine interview, Vonn said she needed to disclose her struggle with depression "to close the chapter and move on".
"Of course I'm afraid that people will judge me, I haven't said anything about it until now," she explained.
"It's a personal matter and you don't talk about that stuff in the media but I feel like it was important for me to say my piece.
"It (depression) is one of the biggest problems that we have right now in the world as far as medical issues go. Anti-depressants are the number two prescriptions.
"It's definitely not a small problem. There has always been a stigma to it and hopefully I can help change that."
Vonn told the magazine her worst period of depression was in 2008 when she could hardly leave her bed and felt "like a zombie".
That was also the year when she won the first of her four overall World Cup titles.
"It has been an interesting ride for me," said Vonn. "I've definitely had a lot of ups and downs, family problems, personal problems, problems on the World Cup tour.
"There is always something going on and I've had a lot of injuries too. Skiing has always been my outlet.
"Whenever I have personal problems skiing has always been there for me. It always makes me happy - it's something I can rely on," said Vonn.
"I'm thankful that I have skiing. It gives me motivation to keep fighting."
- Sports & Recreation