I used to think I was indecisive, but now I'm not so sure.

This is a modern, anonymous one-liner that circulates primarily as a joke in everyday speech, office humor, and collections of “anonymous” quips. It plays on a familiar self-help/therapy vocabulary (“I used to think…”) but subverts it with a punchline that demonstrates the very trait being discussed. Because it is widely repeated without attribution and appears in many informal compilations, it is best treated as a piece of contemporary folk humor rather than a traceable literary aphorism tied to a single author, date, or first publication.

The humor comes from self-referential contradiction: the speaker claims to have moved beyond indecision, yet ends by expressing uncertainty (“not so sure”), which is itself indecisive. The line gently mocks the desire for neat self-knowledge and personal progress, suggesting that some traits are hard to pin down because the act of judging them can reproduce them. As a compact example of verbal irony, it also highlights how language can reveal character unintentionally—what the speaker says undermines what they mean to assert.

1) "I used to be indecisive, but now I'm not so sure."
2) "I used to think I was indecisive; now I'm not sure."
3) "I thought I was indecisive—now I’m not so sure."