Kovalainen could have switched to other categories but elected to help out Caterham with third driver duties which has included several Friday practice sessions.
Those performances put him in the running for the Lotus drive, and he reckons his US GP efforts last weekend proved he did the right thing.
"I never doubted myself, but it is another thing trying to show it and do it," said Kovalainen, who qualified eighth but failed to finish in the points due to a front wing problem.
"You always think that you can do it. That is the reason why I decided to stay still in F1 this year.
"Even if it was as a reserve driver only, I thought I could still do the job. I had to keep working and wait to see if the moment arrives.
"If I got racing again it was more likely that I would race at Caterham, but when this opportunity came it showed that it was worthwhile to stay in F1, and not to switch focus to something else.
"It is funny how quickly things change in F1, and things might change suddenly.
"So you have to keep your focus where your heart feels, where you feel you should be, and try to keep that dream going."
Lotus chiefs were impressed with how quickly Kovalainen got up to speed, especially in making it through to Q3 on his race return - and team boss Eric Boullier thinks he will be much stronger in Brazil this weekend.
"Definitely," he said. "Heikki is a good driver. He's got experience, and maybe he is a bit rusty, but he's going to deliver."
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