Despite impressing in last month's 5-0 thrashing of Serbia, the Newcastle United forward is well aware of the fierce competition for places, and the omission of Jude Bellingham for this month's two internationals underscored the unpredictability of selection.
"At this level, you see the squad changing all the time, players coming in, players leaving," Gordon said from England's camp at St. George's Park.
"You've almost got to be a bit paranoid that you're not going to get in because it pushes you even further.
"You've always got to challenge yourself because the lads you're competing with are always at the highest level because that's the level we're playing at."
England host Wales in a friendly on Thursday at Wembley before heading to Riga for a World Cup qualifier against Latvia, where a victory combined with a draw in the match between Serbia and Albania would guarantee England qualify for the World Cup.
"I never think I'm nailed in, but obviously it's a massive goal for me and one I'm pushing for," the 24-year-old Gordon said.
"It's up to us as players to push ourselves as individuals, and that ultimately challenges the next man in our position to do better again.
"It's a World Cup year, and everyone seems to be flying.
"I think it's more about the team. We have to focus on the team, it's the team that's going to win tournaments, hopefully, and the moment we start making it about individuals is when we've got a problem."
Bellingham's omission raised eyebrows, but Gordon dismissed speculation that the Real Madrid midfielder's place in the team is not guaranteed.
"I think we all know that if (Bellingham) is playing week in, week out for Real Madrid, he is going to be in the England team," he said.
"You definitely notice when he is not here because he is such a big presence, such a big player.
"But he has been injured, he has had a tough couple of months, and it's probably done him some good to be honest because he has played so much football for his age (22)."
Jack Grealish's absence also raised questions, considering the excellent start he has made with Everton and the midfielder is tied atop the list of Premier League assists this season.
"I don't think it's anything to do with them individually, I think they're all at different stages of their career," Gordon said.