Ona za bardzo przejmuje się opinią innych i przez to szybciej się męczy.

Yes. Polish often drops subject pronouns when the subject is clear from the verb.

So:

• Ona za bardzo przejmuje się opinią innych...
• Za bardzo przejmuje się opinią innych...

Both are possible.

Using ona adds emphasis or contrast, for example:

• She, in particular, cares too much about what others think.
• It may suggest a contrast with someone else.

So ona is not required for grammar, but it is natural if the speaker wants to highlight the subject.

Za bardzo means too much or overly.

In this sentence, it modifies przejmuje się, so it means that she cares/worries about others’ opinions more than is healthy or reasonable.

Examples:

• Za bardzo się stresuje. = She stresses too much.
• Za bardzo o tym myślisz. = You think about it too much.

So za bardzo przejmuje się means she worries/cares too much.

Because the verb is przejmować się, which is a fixed reflexive verb meaning to worry about, to care about, or to be affected by something.

Compare:

• przejmować coś = to take over something
• przejmować się czymś = to worry about / care about something

So się is essential here. Without it, the verb would mean something different.

Because przejmować się requires the instrumental case.

The pattern is:

• przejmować się kimś / czymś = to worry about someone / something

So:

• opinia = nominative
• opinię = accusative
• opinią = instrumental

That is why the sentence has:

• przejmuje się opinią

Innych here means others or other people.

More literally:

• opinia innych = the opinion of others
• opinią innych = instrumental form of opinia, plus innych meaning of others

A useful way to see it:

• opinia = opinion
• kogo? czego? = of whom? of what?
• innych = of others

So the phrase means about other people’s opinion or more naturally about what others think.

Przez to means because of that, as a result, or due to that.

In this sentence:

• i przez to szybciej się męczy
• and because of that, she gets tired more quickly

It is similar to dlatego, but not exactly the same in tone.

• dlatego = therefore / that’s why
• przez to = because of that / as a consequence of that

Przez to often points more directly to a cause-and-effect relationship.

Because szybciej is the normal comparative form of the adverb szybko.

• szybko = quickly
• szybciej = more quickly / faster

In Polish, comparatives are often formed as single words rather than with bardziej.

So:

• szybciej się męczy = she gets tired faster / more quickly

Bardziej szybko would sound unnatural here.

Because męczyć się is a common reflexive expression meaning to get tired, to tire easily, or sometimes to struggle depending on context.

Here it means:

• she gets tired

Compare:

• męczyć kogoś = to tire someone, to exhaust someone
• męczyć się = to get tired / to tire oneself / to struggle

So again, się is part of the verb as it is used here.

They are related, but not the same.

• męczy się = she gets tired / she tires herself / she becomes fatigued
• jest zmęczona = she is tired

So:

• męczy się describes a process or tendency
• jest zmęczona describes a state

In this sentence, szybciej się męczy means that she gets tired more quickly, not just that she is tired.

In Polish, the present tense is commonly used for habitual actions and general truths, just like in English.

So:

• przejmuje się = she worries/is worrying, but here really she tends to worry
• męczy się = she gets tired / tends to get tired

The sentence is describing her usual behavior, not just one single moment.

Because the sentence describes an ongoing tendency or repeated behavior, not a single completed event.

• przejmować się is imperfective
• męczyć się is imperfective

Imperfective verbs are used for:

• habits
• repeated actions
• general descriptions
• ongoing processes

That fits this sentence perfectly: she generally worries too much, and as a result she generally gets tired faster.

The word order is somewhat flexible, but not completely free.

For example, these are possible:

• Ona za bardzo przejmuje się opinią innych.
• Ona się za bardzo przejmuje opinią innych.

Both can sound natural, though the first is very standard.

Polish often places się near the verb, but its exact position can shift depending on rhythm, emphasis, and style.

Still, some placements sound much more natural than others, so for learners it is safest to stay close to the original pattern:

• przejmuje się
• się męczy

Yes, absolutely.

The Polish phrase is structurally closer to:

• the opinion of others

But in natural English, we often say:

• what others think
• other people’s opinions

So the Polish grammar is a bit more noun-based, while English often prefers a clause-like expression.

All of these are good ways to understand the phrase:

• opinią innych
• others’ opinion
• other people’s opinion
• what others think