Britton struggled to find a role during Paul Clement's early tenure as manager at the Swans, although the 34-year-old returned during the back-end of the 2016-17 campaign in order to help guide his club to an unlikely relegation escape.
"There have been times like that [thinking about retirement], I'm not going to lie," said Britton, according to Sky Sports News.
"There are times when you train hard, but if you're not playing on the weekend it's difficult. As much as I love training, there's no better buzz as a footballer than stepping out on the pitch and playing.
"I've got this year with the option of another year, depending on how many games I play. So if the worst-case scenario was I didn't hit the amount of games, then we'd have to see what happens at the end of the season. But I still feel fit, I still feel strong."
Swansea start their new Premier League campaign when they face Southampton on Saturday afternoon.