Kane reveals doubts during journey to the top
The 24-year-old, who was loaned out to the likes of Leyton Orient and Millwall in the early stages of his career, on Friday signed a new six-year contract at Tottenham after scoring 30 Premier League goals in 2017-18.
Kane established himself as a first-team regular for Spurs in 2014-15 but had thoughts it would not happen during difficult spells in the lower leagues.
"There were times when it was tough," he told Sky Sports, speaking before his new deal at Spurs was announced.
"There were times when I wasn't playing in the Championship and I was thinking to myself, 'I'm so far away from the England team – how long is it going to take me to get there?'
"I always stayed focused and believed I could. It was just a matter of working hard and that's what I did. Now it's about maintaining that and working even harder to stay at the top level."
England captain Kane is nervous about his first appearance in the World Cup, though he acknowledged there will be similar feelings for all teams.
After scoring in a 2-1 friendly victory over Nigeria, Kane was an unused substitute in England's final warm-up game – a 2-0 win over Costa Rica.
The Spurs striker, who scored five goals in six qualifying appearances for England, said the World Cup offered him an opportunity to prove himself on the biggest stage.
"There's definitely pressure but that's natural – that's part of the job and part of the game," he said.
A good way to start our warm-up games. Lots of positives to take and a win #ThreeLions pic.twitter.com/Ju4EjQDBRZ
— Harry Kane (@HKane) June 2, 2018
"Every time I put on the shirt I want to prove to everyone that I'm one of the best. There's going to be a lot of pressure on us this World Cup but there's pressure for every big team that's there.
"This is going to be my first one so I'm excited, there's going to be nerves and we're going to be feeling a bit of pressure but I try and take that in my stride."