Sergery Sirotkin spent two seasons as Renault’s development driver but wasn’t given the opportunity to progress and drive for the team.
Williams however gave him a seat and Sirotkin acknowledged this.
Sirotkin was hoping he was offered a place on the grid with Renault towards the end of last season however Renault chose Carlos Sainz and Nico Hulkenberg ahead of him.
Prior to his job at Renault, the Russian spent time as a Sauber test driver.
The now Williams driver said: “With Sauber, it was not really a full focus on (an F1 seat), it came as quick as it disappeared to be honest.
“I was still doing my career in World Series and GP2 and ok it was a good opportunity but at the end of the day it was not something I put all my life into. I was still racing and winning the racing and hitting my own targets and that’s what I was trying to continue to do.
“It was a bit more difficult with Renault last year, because it was the first season I didn’t race when I was fully dedicated to the team and I worked hard for them.
“Then at some points, when you realise it’s not going the way you expected it to be going, it’s definitely not the best feeling. I was still traveling, still doing a lot of work and then not so much time behind the wheel so you don’t get as much satisfaction back.
“It’s not the easiest feeling and its a period that ended up being much more difficult than I imagined it to be. But I learned from it and I maximised it and I need to thank them as well for me making the driver I am now and getting me where I am now.”
Sirotkin will make his F1 debut in just over a weeks time.