Did Naruto Really Say “Hard Work Is Worthless for Those That Don't Believe in Themselves”?

No. Naruto Uzumaki does not say "hard work is worthless for those that don't believe in themselves," and neither does Rock Lee, the other name it travels under. The sentence is Might Guy's, said to Lee, and the version that circulates is a fan translation of a line whose official English is on the record.

The verdict

Misattributed, in fan wording. Wikiquote's Naruto page records the line under season 2, episode 14, in the Chunin Exam arc, in the dub's words: "All the effort is pointless if you don't believe in yourself!" The speaker is Guy, and the scene is his conversation with Lee about talent and perseverance, the one that ends with Guy telling him that the gift of perseverance is what makes him a genius too. The meme's wording, "hard work is worthless for those that don't believe in themselves," is the same sentence as it appeared in a subtitle or a scanlation, and the quote sites that carry it have attached it to whichever Naruto character was nearest.

How it drifted

The drift runs in two steps. First the speaker: the line is about Lee, spoken to Lee, and in a screenshot of the scene Lee is often the face on screen, so "Rock Lee" became the attribution on a good share of posts. Then the series: once a Naruto quote is loose on the internet, "Naruto" becomes the attribution by default, because the character and the show share a name and a caption reading "Naruto" is ambiguous in exactly the way a quote aggregator does not check. By the time the line reaches a motivational account it is Naruto Uzumaki's, and the man who said it is a joke character with a bowl cut whom the account has never heard of.

Why it is Guy's line and nobody else's

Guy is the series' argument that effort is a discipline rather than a consolation prize, and this sentence is the argument's hinge. He is not telling Lee that hard work guarantees anything; he is telling him that hard work without self-belief is wasted, which is a colder and more precise claim, and it is the claim Lee's whole arc tests. Put in Naruto's mouth it becomes generic encouragement. Put in Lee's it becomes a student quoting his teacher. Guy's own version, on his page with its source, is the only one where the speaker has the standing to say it.

What Naruto actually says about effort

Naruto's version of the same idea is the nindo, "I never give up, I never go back on my word, that's my ninja way," which is on his page and is a promise rather than an observation. The difference is the tell: Naruto makes vows, Guy makes rules. A sentence that sounds like a rule about effort is nearly always Guy's, and a search of his page on Wikiquote settles which one.

How we checked

The verification process asks for a primary or editorial source, and this line has one: Wikiquote's episode-numbered transcript, which gives the speaker, the episode and the dub's wording. Nothing attributes it to Naruto with a scene, because there is no scene. It sits in the fact-check database as misattributed, which is the verdict for a real line filed under the wrong name; the rest of the series is on the Naruto hub.