This sentence works because:
* It's relatable: Many people have a playful relationship with food.
* It's unexpected: The joke lies in the double meaning of "seafood diet."
* It's short and punchy: This makes it memorable and easy to deliver.
Here are some other options:
* "I'm not sure what's wrong with my car, but it keeps driving me to the donut shop."
* "I used to be addicted to soap, but I'm clean now."
* "I'm not lazy, I'm just highly motivated to do nothing."
Ultimately, the best sentence for humor depends on the context and audience.