Lewis Hamilton feels "almost helpless at some points" in the face of the problems that have hit him this season.
The Mercedes driver qualified 10th for Sunday's Russian Grand Prix after the recurrence of an engine failure that put him at the back of the grid at the previous race in China.
He is 36 points behind team-mate Nico Rosberg, who starts the race from pole.
"The goal is moving further into the distance and there is nothing I can do," Hamilton said.
Sunday's race is live on Radio 5 live Sports Extra and the BBC Sport website at 13:00 BST.
The Briton has hit trouble in every race so far this season, finishing second, third and seventh while Rosberg has taken three victories.
But the world champion said he was still confident he could turn the season around.
"There is still a long way to go," he said. "Once again, always trying to turn the negatives into positives.
"It is another big challenge and the challenge is becoming great but every challenge is an opportunity to rise. I quite like that approach and idea.
"Even when it seems like it's the darkest of days, there is always some light there. That is what is going to power me forward for tomorrow."
Mercedes Formula 1 boss Toto Wolff said: "You need to accept that someone who has had multiple situations like this, technical problems, is upset.
"He doesn't need anyone to build him up. He is very strong. He is going to get over it.
"He is a fighter and he has been in this situation many times on his life and it will have no effect on him, even though at the moment it is clear he is not in the best of moods."
Mercedes have fitted to Hamilton's car the engine he used in practice and qualifying in the last race in China, and which suffered an identical MGU-H failure to the one in Sochi on Saturday.
It has a new turbo and MGU-H, as well as a new control electronics unit and energy store to eliminate that as a source of the problem.
They flew in a new fuel system overnight as all Mercedes engines in Russia had been fitted with an updated one, and parts have to be replaced like-for-like on reliability grounds to avoid grid penalties.
Hamilton said on Saturday evening that he was mystified as to why his Mercedes was suddenly suffering reliability problems after the car ran trouble-free in pre-season testing and the first two races.
"I am very curious as to what is going on so I have asked them to give me as much detail as possible because we did 800km a day in testing and the car was faultless and all of a sudden two times in a row the same thing," he said.
"That doesn't happen for us. They say we have understood what happened in the last race and I would have thought we would have learned but obviously not and so more work needs to go in.
"We have another engine going in and who's to know it's not going to happen on that one?
"And we'll have to be careful how we pick out all the other engines in the year because now I have only three for the rest of the year so I am going to have another penalty later in the year at some point."
He said his initial focus in the race on Sunday would be to avoid trouble at the first corner - his car has suffered damage in first-corner incidents in all three races so far.
"I am just hoping to have a clean first lap and have a car in one piece to be able to fight with people," Hamilton said.
Rosberg's other main rival, Ferrari's Sebastian Vettel, starts seventh as a result of a five-place grid penalty for an unauthorised gearbox changes.
Rosberg said: "Of course the others have been unfortunate, extremely unfortunate, and that makes my race a little easier tomorrow but an F1 race is never easy. The opposition are still there and still need to stay focused an do the job as well as possible."
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