Uncle Ben would be proud.
Amazing Spider-Man (Vol. 1) #181
Published: c. March, 1978?
Cover Date: June, 1978
“Flashback!”
Writer: Bill Mantlo, Archie Goodwin, and Len Wein
Artist: Sal Buscema
Inker: Mike Esposito
Letterer: Annette Kawecki
Colorist: Glynis Wein
I know he quits in the MJ origin story. And again in a Secret Wars II tie-in. Spider-Man vs. Wolverine. The 90s Clone Saga. When he and MJ moved to Portland. The Final Chapter.
Some of these quits are 1 (or less-than 1) issue, but he still quits.
@hornacek: I can only think of around 2 or 3 times.
How many times after Spidey made this (silent) speech did Peter quit being Spider-Man? Half a dozen?