How can a person arrive to a destination before they've departed? The metaphor isn't meant to be understood in the literal sense. The passage's context describes an individual being close-minded and whose opinion is already formed. Read it once or twice more to let the text sink in.
Why should it be only the man who knows how things alternate and whose heart approves its own judgements who has such an authority?
The fool has one just as he has. For there to be 'That's it, that's not' before they are formed in the heart would be to 'go to Yueh today and have arrived yesterday.'
Chuang-Tzu was criticizing the philosophers of his time for their close-mindedness. I believe his critique carries over into the present day. When it comes to certain subjects and beliefs people can be stubborn. This is especially true in health and fitness.
When a person is looking for an answer in regards to diet or exercise, the majority of reactions fall under these 3 categories:
It's common for "affirmation" to be paired with either of the other two (not always). A person wants to be assured their way is the "right way" while they dismiss or ignore other information they come across.
Affirmation: They're looking for someone to agree with them instead of learning more and expanding their knowledge.
Dismissal: It's not congruent with what they think thus making it incorrect.
Ignore: The information isn't understood and therefore not registered in their mind.
Avoid this mistake if you want to make progress and improve. If you don't, why go to the gym or diet today if you've already determined your limits yesterday?