Learn Hardcore Spanish (Latin America): Mi abuela dice que hay que cuidar el corazón, no solo el cuerpo. - My grandmother says you have to take care of the heart, not just the body.

“Hay que” is an impersonal expression that means “one must,” “you have to,” “we should,” “it’s necessary to.” It doesn’t say who has to do the action.

hay que cuidar el corazón
→ one must take care of the heart / we should take care of the heart

There is no specific subject (I/you/we); it’s a general rule or recommendation.

“Tener que” does have a subject and is more personal/obligatory:

Tengo que cuidar el corazón.
→ I have to take care of my heart.
Tenemos que cuidar el corazón.
→ We have to take care of our hearts.

So:

hay que + infinitive = general necessity/obligation
tener que + infinitive = specific person’s obligation

Why is there a “que” after “dice”? Can I say “Mi abuela dice hay que cuidar…” without “que”?

In Spanish, when you report what someone says, thinks, or believes, you almost always use “que” to introduce the clause. It’s like “that” in English, but in Spanish it is usually not optional.

Mi abuela dice que hay que cuidar el corazón.
→ My grandmother says (that) we must take care of the heart.

Saying:

Mi abuela dice hay que cuidar el corazón.

sounds incorrect or very unnatural in standard Spanish. You need:

dice que…, piensa que…, cree que…, opina que…, etc.

Why isn’t there a subject before “hay que cuidar”? Who is supposed to take care of the heart?

There is no subject because “hay que” is an impersonal structure. It’s understood to mean something like:

people in general must…
we all should…
you should… (in a general sense)

So:

hay que cuidar el corazón
≈ we should all take care of our hearts / you have to take care of your heart / one must take care of the heart.

Spanish leaves it general on purpose. If you want to specify who:

Yo tengo que cuidar el corazón. – I have to…
Todos tenemos que cuidar el corazón. – We all have to…

Why do they say “el corazón” and “el cuerpo” instead of “tu corazón” or “tu cuerpo”?

Spanish often uses the definite article (el, la, los, las) for:

body parts
general organs
general concepts

where English often uses “your” or no article:

Lávate las manos. – Wash your hands.
Me duele la cabeza. – My head hurts.
Cuidar el corazón, no solo el cuerpo. – Take care of your heart, not just your body.

So in this sentence, “el corazón” and “el cuerpo” are general, but in context we understand “your heart / your body” (or our hearts/bodies).

Could I say “cuidarse el corazón” instead of “cuidar el corazón”? What’s the difference?

Both forms exist, but there is a nuance:

cuidar + direct object
→ to take care of (something)
- Hay que cuidar el corazón.
  One must take care of the heart.
cuidarse + body part (reflexive)
→ to take care of oneself / to look after (one’s own …)
- Hay que cuidarse el corazón.
  You have to take care of your heart.

In many contexts, especially with health, people say:

Hay que cuidarse. – You have to take care of yourself.
Tengo que cuidarme el corazón. – I have to take care of my heart.

In your sentence, “cuidar el corazón” sounds more general and abstract: not just your own heart, but the heart as something important; it can be both physical and emotional.

Is “corazón” here only physical (the organ), or can it also mean emotions, like “heart” in English?

In Spanish, “corazón” can also be literal or metaphorical, just like in English.

In this sentence:

cuidar el corazón, no solo el cuerpo

it can be understood as:

physical: take care of your heart (cardiovascular health)
emotional/spiritual: take care of your feelings, emotional life, inner self

Many Spanish speakers will naturally read both layers:
take care of your emotional life, not just your physical body.

Why does the sentence say “no solo el cuerpo” and not something like “no solo el cuerpo sino también el corazón”?

The full contrast structure in Spanish is usually:

no solo X, sino (también) Y
→ not only X, but (also) Y

For example:

Hay que cuidar no solo el cuerpo, sino también el corazón.

In your sentence:

Mi abuela dice que hay que cuidar el corazón, no solo el cuerpo.

the second part (“sino también el corazón”) is basically implied and not repeated to avoid redundancy. The idea is still:

We must take care of the heart, not only the body (but also the heart).

It’s a common, natural ellipsis in conversation.

Why is “dice” in the present tense and not “dijo”? What difference would “Mi abuela dijo…” make?

Mi abuela dice que… (present)
suggests something she says regularly, a typical piece of advice or a habitual saying.
→ My grandmother says (she always tells me) that we must take care of the heart…
Mi abuela dijo que… (simple past)
refers to something she said on a specific occasion in the past.
→ My grandmother said (on that day) that we had to take care of the heart…

So the present tense “dice” gives the idea of a repeated or ongoing piece of advice, almost like a motto.

Could I move the words around and say “Mi abuela dice que el corazón hay que cuidarlo…”? Does that change the meaning?

Yes, you can say:

Mi abuela dice que el corazón hay que cuidarlo, no solo el cuerpo.

Here:

el corazón appears first.
lo (in cuidarlo) is a pronoun that refers back to el corazón.

This structure:

el corazón hay que cuidarlo

adds emphasis on el corazón:

literally: the heart, one must take care of it
feels like: the heart is what we must (really) take care of

Meaning is basically the same, but the focus shifts more strongly to the heart.

How do you pronounce “hay” in “hay que cuidar”, and is the “h” silent?

“hay” is pronounced like “eye” in English.
The “h” is completely silent.

So:

hay que → roughly /ai ke/

Also, note that “hay” here is the form of the verb “haber” meaning “there is / there are”, but in the expression “hay que + infinitive” it becomes “it is necessary to / one must.”