Robert Kubica has admitted it "wasn't easy" to turn down the chance of driving as a Ferrari development driver in 2019.
Kubica was understood to be in talks with Ferrari to take up a simulator position following the exit of its reserve drivers Antonio Giovinazzi and Daniil Kvyat to Sauber and Toro Rosso, respectively.
The Polish driver is making an incredible return to the sport; after an eight-year absence, with Kubica signing for Williams to drive alongside George Russell for the 2019 F1 season.
"I knew what I would have liked to do, but sometimes things are a bit more complicated than they look from the outside," Kubica explained to Motorsport.com.
"I had some opportunity which I think was very interesting and it was not easy to say no. In the end, I am a racing driver - even though I haven't been racing for quite a long time - and this racing mentality has won out.
"I'm happy to have made this decision because it is a big challenge."
Kubica is adamant that he is well prepared for his return to F1 following a horrific rally-crash back in 2011.
"It's not easy to become an F1 driver; it's not easy to convince people you can do it and establish yourself in an F1 paddock," Kubica continued. "You have to have a lot of drive to do it because I went through this 12 years ago, and in the end, I said I think I have the energy to do it again."