Learn Hardcore Icelandic: Ég hugsa líka um heilsuna mína til að vera heilbrigður. - I also think about my health in order to be healthy.

Ég hugsa um heilsuna mína = “I think about my health.”
The verb is hugsa (“to think”) and um is the preposition “about, around.”
hugsa um + accusative is the normal, neutral way to say “think about (something/someone).”

There is also pæla í (“to ponder, think deeply about”), which is more informal/colloquial, but hugsa um is the safest choice in standard language.

Why is it um heilsuna and not um heilsu or something else? What case is being used?

The noun heilsuna is in the accusative case, singular, definite.

The base word is heilsa (health) – a feminine noun.
The preposition um (“about”) normally takes the accusative case.
Feminine heilsa in the accusative singular definite is heilsuna:
- nominative: heilsa
- accusative indefinite: heilsu
- accusative definite (with the article): heilsuna (“the health”)

So after um, you put heilsuna: um heilsuna = “about the health / my health.”

Why do we say heilsuna mína and not just heilsa mín? How do possessives work here?

In Icelandic, when you say “my X,” you generally use a definite noun + possessive pronoun after it:

bókin mín – “my book” (literally “the book my”)
bíllinn minn – “my car”
heilsa mín (nominative) – “my health”

In the sentence:

The noun is object of um, so it must be accusative: heilsu-.
You still keep the definite ending to show it’s “the/my health”: heilsu + na → heilsuna.
Then you add the possessive mína after the noun.

So: um heilsuna mína = “about my health”.
Word-for-word: “about the-health my” (accusative).

Why is it mína and not mín or mínum? How is mín changing here?

Mín / mína / mínum / minnar are all forms of the same word: “my” (feminine singular), changing for case and gender like an adjective.

Here, mína agrees with heilsuna:

heilsa is feminine.
In the sentence, heilsuna is accusative singular definite (object of um).
So mín must also be feminine accusative singular → mína.

Rough mini-paradigm for feminine singular mín:

Nominative: mín – heilsa mín (my health – subject)
Accusative: mína – um heilsuna mína (about my health)
Dative: minni – frá heilsu minni (from my health – more abstract context)
Genitive: minnar

So the form mína is required by the grammar (feminine + accusative).

Could I say Ég hugsa líka um heilsu mína without the -na ending? Would that still be correct?

Ég hugsa líka um heilsu mína would sound odd or incorrect to most native speakers.

Reasons:

With a possessive pronoun like mín, you normally use the definite form of the noun:
- correct: Ég les bókina mína. – I read my book.
- analogously: Ég hugsa um heilsuna mína. – I think about my health.
heilsu (without -na) is the indefinite accusative form (“health” as a bare mass noun), and combining that with mína (my) is not the normal pattern.

So the natural, idiomatic version is um heilsuna mína.

What exactly does til að vera mean, and why is til að used instead of just að vera heilbrigður?

Til að before an infinitive verb phrase expresses purpose: “in order to / so as to.”

til = “to, for”
að = infinitive marker (“to” before verbs)

So:

til að vera heilbrigður = “(in order) to be healthy.”

If you said just að vera heilbrigður, that could be a neutral infinitive clause (“to be healthy” in a more abstract sense), but til að makes the purpose clear:

Ég hugsa líka um heilsuna mína til að vera heilbrigður.
“I also think about my health in order to be healthy.”

Why is it heilbrigður and not something like heilbrigð or heilbrigða? What does this ending depend on?

Heilbrigður is an adjective meaning “healthy.”
In this sentence it is a predicate adjective, and it must agree with the subject (ég) in gender, number, and case.

If the speaker is a man (or grammatically masculine subject):
→ Ég er heilbrigður.
→ til að vera heilbrigður.
If the speaker is a woman (or grammatically feminine subject):
→ Ég er heilbrigð.
→ til að vera heilbrigð.
For a neuter subject like barnið (the child):
→ Barnið er heilbrigt.
→ til að vera heilbrigt.

So heilbrigður is masculine nominative singular, matching a masculine ég. A female speaker would naturally say til að vera heilbrigð instead.

Why is líka placed after hugsa? Could I say Ég líka hugsa um heilsuna mína or Ég hugsa um heilsuna mína líka?

Líka means “also / too,” and Icelandic has fairly strict word order around the finite verb (here: hugsa).

In main clauses, the finite verb usually comes in second position.
Adverbs like líka typically come after that verb.

So:

Standard: Ég hugsa líka um heilsuna mína…
(Subject Ég – verb hugsa – adverb líka – rest.)

The alternatives:

Ég líka hugsa …
→ Sounds wrong; líka is incorrectly placed before the finite verb.
Ég hugsa um heilsuna mína líka.
→ This is grammatical and means “I think about my health too/as well.”
It tends to stress heilsuna mína as the thing that is “also” being thought about (as opposed to something else).

So Ég hugsa líka um heilsuna mína is the neutral, default word order; moving líka changes the focus/emphasis.

What is the difference between heilsa and heilbrigður? They both seem related to “health.”

They are related but different parts of speech:

heilsa – a noun, “health.”
- heilsan / heilsuna = “the health”
- heilsu appears as a case form (e.g. accusative, dative).
heilbrigður – an adjective, “healthy.”
- masculine: heilbrigður
- feminine: heilbrigð
- neuter: heilbrigt

In the sentence:

heilsuna mína = “my health” (noun phrase).
vera heilbrigður = “to be healthy” (verb + adjective).

If I want to say “I take care of my health” rather than just “I think about my health,” should I still use hugsa um?

“I think about my health” and “I take care of my health” are not the same in Icelandic.

Ég hugsa um heilsuna mína = “I think about my health.”
(Mental activity – thinking, considering.)

To express “take care of my health,” you’d usually say:

Ég hugsa vel um heilsuna mína.
(Literally: “I think well about my health,” but idiomatically: “I take good care of my health.”)

The adverb vel (“well”) with hugsa um often carries the meaning of “look after / care for”:

Hún hugsar vel um barnið. – She takes good care of the child.

So for the original sentence, if you actually mean “I take care of my health in order to be healthy,” a more natural Icelandic version would be:

Ég hugsa vel um heilsuna mína til að vera heilbrigður / heilbrigð.