The coach has guided the Three Lions to the Euro 2020 final and the semi-finals of the 2018 World Cup during his eight-year tenure but knows that failure to bring home silverware in Germany this summer could spell the end of his time as boss.
Southgate told the German newspaper Bild: "If we don't win, I probably won't be here anymore. Then it might be the last chance.
"If we want to be a big team and I want to be a top coach, then you have to deliver in the big moments."
He added: "I think about half of the national coaches leave after a tournament - that's the nature of international football.
"I've been here for almost eight years now and we've come close. So I know that you can't keep standing in front of the public and saying, 'Please do a little more', because at some point people will lose faith in your message."
Southgate's contract expires later this year and he chose not to sign a new deal before the Euros as it would have piled more "pressure" on his players at the tournament.
He said: "The reason is that there would have been more criticism, which would have put more pressure on the team.
"England did that once before with Fabio Capello and there was a big drama before the tournament. It's better to check yourself after the tournament."