Learn Hardcore Portuguese (Portugal): O terapeuta disse que o descanso faz parte do tratamento, não é preguiça. - The therapist said that rest is part of the treatment, it is not laziness.

O terapeuta = the therapist (a specific one already known in the context)
Saying just Terapeuta disse... sounds incomplete or telegraphic, like a note or a headline, not a normal sentence.

So O terapeuta disse... is the natural, full way to say “The therapist said…”.

Does o terapeuta mean the therapist is male? Could it also be female?

Yes, the article shows grammatical gender:

o terapeuta = grammatically masculine → usually interpreted as a male therapist
a terapeuta = grammatically feminine → usually a female therapist

The noun terapeuta itself ends in -a but is epicene (can be masculine or feminine depending on the article and context), so the article is what tells you the gender here.

Why is it disse que o descanso faz parte and not something like disse que o descanso fazia parte (past tense) after disse?

Portuguese reported speech is more flexible with tenses than English:

In English you often backshift:
- He said that rest *was part of the treatment.*
In Portuguese you can backshift (fazia parte), but if what was said is still true now, the present tense is very common and natural:
- O terapeuta disse que o descanso faz parte do tratamento.
  → The therapist said this, and it is still true that rest is part of the treatment.

So the present faz highlights that this is a general, ongoing truth, not something only true in the past.

What exactly does faz parte mean here? Why not just é parte or é uma parte?

Fazer parte (de) is a very common fixed expression meaning “to be part (of), to belong (to)”:

O descanso faz parte do tratamento.
= Rest is (an integral) part of the treatment.

You can say:

O descanso é parte do tratamento. (correct, but slightly less idiomatic)
O descanso é uma parte do tratamento. (also correct, but sounds more like “one of the parts”, a bit more technical)

The most natural everyday choice in Portuguese for this idea is fazer parte de.

Why is it do tratamento and not de o tratamento?

Portuguese almost always contracts the preposition de with the definite article o / a / os / as:

de + o = do
de + a = da
de + os = dos
de + as = das

So grammatically it’s:

faz parte de o tratamento → spoken and written as faz parte do tratamento.

Saying de o tratamento separately is incorrect in normal Portuguese.

Why is descanso used as o descanso (with an article)? Could you say just descanso faz parte do tratamento?

Here descanso is a noun (rest), and in Portuguese, abstract nouns like this are usually used with an article when you’re talking about them in a concrete, specific way:

O descanso faz parte do tratamento.
= Rest (as a defined thing in your treatment plan) is part of the treatment.

You could say Descanso faz parte do tratamento, but:

It sounds more like a headline, slogan, or note (article dropped for stylistic reasons), not like normal flowing speech.

In ordinary speech or writing, O descanso faz parte... is the natural choice.

In não é preguiça, what is the subject? Why is there no isso?

The subject is understood from context. The sentence really means:

(Isso) não é preguiça.
= (That) is not laziness.

In Portuguese, when the subject is obvious (usually isso = that / this referring to what was just mentioned), it’s very common to omit it:

O descanso faz parte do tratamento, não é preguiça.
= Rest is part of the treatment; it’s not laziness.

So não é preguiça is a natural shorthand for isso não é preguiça.

Could I also say não é por preguiça? Would it mean the same thing?

Very close, but with a nuance:

não é preguiça
= it’s not laziness (identifies what it is / isn’t)
não é por preguiça
= it’s not *because of laziness (talks about the *reason/motive)

In the sentence:

O terapeuta disse que o descanso faz parte do tratamento, não é preguiça.

you could indeed say:

..., não é por preguiça.

Both are idiomatic.
não é preguiça is a bit more direct and categorical;
não é por preguiça explicitly denies laziness as the motive.

Could I rephrase O descanso faz parte do tratamento with an infinitive, like Descansar faz parte do tratamento?

Yes:

O descanso faz parte do tratamento.
= Rest is part of the treatment. (noun)
Descansar faz parte do tratamento.
= Resting is part of the treatment. (verb used as a noun → “to rest” / “resting”)

Both are correct and natural.
O descanso focuses slightly more on the thing (the rest periods);
Descansar focuses a bit more on the action of resting. In practice, they’re very close in meaning.

How would a European Portuguese speaker pronounce this whole sentence?

In simplified IPA for European Portuguese:

O terapeuta disse que o descanso faz parte do tratamento, não é preguiça.
/u tɨɾɐˈpɐwtɐ ˈdisɨ kju dɨʃˈkɐ̃su faʃ ˈpaɾt(ɨ) du tɾɐtɐˈmẽtu, nɐ̃w ɛ pɾɨˈɡisɐ/

Key points:

O terapeuta → u tɨɾɐˈpɐwtɐ
disse → ˈdisɨ
que o often sounds like kju in connected speech.
descanso → dɨʃˈkɐ̃su (the s between vowels → [z] or [z]-like, but in d‑ESCAN‑so it’s [s] before consonant; the e in de is very reduced)
faz → faʃ (final z-sound written as z/s often goes to [ʃ] in EP)
parte → ˈpaɾt(ɨ) (final e is very reduced or almost gone)
tratamento → tɾɐtɐˈmẽtu
preguiça → pɾɨˈɡisɐ (the ç has an s sound).

This is a careful but natural European Portuguese pronunciation.