Russell denied that he would potentially make the move to any other midfield team, insisting that only a Mercedes call-up would sway him away from Williams.
"The only way I wouldn't be at Williams next year is if I was in a Mercedes," Russell said. "But I'm absolutely committed to Williams at the moment.
"If the opportunity came along at Mercedes, that would obviously be fantastic, but that's not at the forefront of my mind.
"I'm just fully focused here [at Williams], and everything we're doing now is also working towards next year's car and making that to a much better level than our current car is."
Williams has failed to make it out of Q1 so far this year, and has been far away from the pace of its rivals.
Despite consistently competing at the back of the field this season after winning consecutive championships in GP3 and Formula 2, Russell says he is not finding it difficult to keep his motivation up.
"It's not difficult to stay motivated," Russell stated. "The fact is, I'm being paid to do something I love, driving a Formula 1 car that is incredibly fast.
"Even though we're the slowest car, in the scheme of things it's incredibly fast, week in, week out. I'm still moving that side of things and the fact that I still see a light at the end of the tunnel helps keep morale high.
"If we didn't understand why we were slow if we saw no progress moving forward, then obviously it would be more difficult to keep your chin up. But at the moment we do see progress and light at the end of the tunnel."
Bahrain International Circuit - Winter testing
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