wǒ zhàn zài jìngzi qián shuāyá de shíhou, juéde zìjǐ jīntiān kànqǐlái hěn lèi.

Yes. 站在镜子前刷牙的时候 is a time phrase/clause meaning when I was standing in front of the mirror brushing my teeth.

A very common Mandarin pattern is:

[action / situation] + 的时候, [main clause]

So here:

• 站在镜子前刷牙的时候 = when standing in front of the mirror brushing my teeth
• 觉得自己今天看起来很累 = I felt that I looked very tired today

This is similar to English When ..., ....

站在 means to stand at / stand in / stand on / stand by somewhere.

• 站 = to stand
• 在 = at / in / on; it introduces the location

So:

• 站在镜子前 = stand in front of the mirror

This is a very common structure:

verb + 在 + place

Examples:

• 坐在椅子上 = sit on the chair
• 写在纸上 = write on the paper
• 住在北京 = live in Beijing

So 站在 is not redundant. 站 tells you the action, and 在 introduces where.

前 means front / before.

In 镜子前, it means in front of the mirror. This is a compact and natural way to say it.

You can think of the pattern as:

noun + 前 / 后 / 上 / 下 / 里
= front of / behind / on / under / inside

So:

• 镜子前 = in front of the mirror
• 门后 = behind the door
• 桌子上 = on the table

You may also hear:

• 在镜子前面

This is also correct and a bit fuller. But 在镜子前 is very natural and common.

It is basically two actions happening together:

• 站在镜子前 = standing in front of the mirror
• 刷牙 = brushing one’s teeth

Mandarin often puts actions next to each other without adding words like while or and if the relationship is clear.

So this part means something like:

• standing in front of the mirror brushing my teeth
• or while standing in front of the mirror, brushing my teeth

This kind of verb sequence is very normal in Chinese.

Yes, you can say 刷牙时, and it is shorter and slightly more written or formal.

The full pattern is:

verb phrase + 的时候

So:

• 刷牙的时候 = when brushing teeth
• 我刷牙的时候 = when I brush / when I was brushing my teeth

In this sentence, the whole phrase is actually:

站在镜子前刷牙的时候

The 的 links the action phrase to 时候.

A shorter version is:

• 站在镜子前刷牙时

That is grammatical, but 的时候 sounds very natural in everyday speech.

Because the subject is already clear.

The sentence is:

• 我站在镜子前刷牙的时候，觉得自己今天看起来很累。

After the comma, Mandarin often omits the subject if it is obviously the same person. English often repeats the subject, but Chinese frequently does not.

So this is understood as:

• 我...的时候，(我)觉得...

If you said the 我 again, it would still be grammatical:

• 我站在镜子前刷牙的时候，我觉得自己今天看起来很累。

But leaving it out is very natural.

In this sentence, 觉得 is best understood as feel or think/feel.

• 觉得 often expresses a personal judgment, impression, or feeling.
• It is very common before clauses and adjectives.

Here:

• 觉得自己今天看起来很累 = felt that I looked very tired today = thought I looked very tired today

So 觉得 does not mean a physical sensation only. It often means to feel / to think in one’s opinion.

Examples:

• 我觉得他很好。 = I think he is very nice.
• 我觉得有点冷。 = I feel it’s a bit cold.

自己 means oneself / self.

In this sentence:

• 觉得自己今天看起来很累 = felt that I myself looked very tired today

Using 自己 is natural because the speaker is making a judgment about their own appearance.

If you used 我 here, it would sound less natural in this structure. Chinese often uses 自己 when the object refers back to the subject.

Compare:

• 我觉得自己很累。 = I feel tired.
• 她觉得自己很累。 = She feels tired.

So 自己 works reflexively: it refers back to the subject.

看起来 means to look / to appear / to seem.

So:

• 自己今天看起来很累 = I look very tired today

If you only say:

• 自己今天很累

that means:

• I am very tired today

That describes your actual condition.

But:

• 自己今天看起来很累

describes appearance:

• I look tired today
• I seem tired today

So 看起来 is important because the speaker is noticing their appearance in the mirror.

今天 is the time word today, and in Chinese, time words usually come before the main predicate or before the part they modify.

So:

• 自己今天看起来很累 = I today look very tired

This is natural Chinese word order.

You could also hear:

• 觉得自己看起来今天很累

but that is less natural here.

The most natural placement is before 看起来, because 今天 sets the time frame for the whole judgment: today, I look tired.

A simple rule:

• time words usually come before the verb/adjective phrase

Examples:

• 我今天很忙。 = I’m busy today.
• 他昨天没来。 = He didn’t come yesterday.

Here, 很 can mean very, but in many basic adjective sentences it also functions as a normal linker and does not always sound strongly like very.

In Mandarin, adjectives often need something before them when they are the main predicate.

So:

• 很累 = tired / very tired, depending on context

In this sentence, 很累 naturally means:

• very tired or at least
• quite tired

But structurally, 很 also helps the sentence sound complete and natural.

Compare:

• 我累。 = possible in certain contexts, often contrastive or emphatic
• 我很累。 = normal, natural statement

So yes, it can mean very, but do not always translate 很 mechanically.

It can mean both, depending on context.

• 累 basically means tired
• In a sentence with 看起来, it often describes appearance: looking tired / worn out / exhausted

So here, because the speaker is looking in the mirror, 看起来很累 means:

• looked tired
• looked worn out
• looked exhausted

It is about appearance, not necessarily only actual physical fatigue.

The comma is helpful because it separates the time/background part from the main statement.

• 我站在镜子前刷牙的时候，觉得自己今天看起来很累。

Before the comma:

• background / time situation

After the comma:

• what the speaker realized or felt

In spoken Chinese, this would be a pause. In writing, the comma makes the structure clearer.

You may sometimes see Chinese sentences without commas in informal writing, but here the comma is standard and useful.

A more natural way to process it is in chunks:

1. 我
   = I

2. 站在镜子前刷牙的时候
   = when I was standing in front of the mirror brushing my teeth

3. 觉得
   = felt / thought

4. 自己今天看起来很累
   = I looked very tired today

So the whole sentence is:

• When I was standing in front of the mirror brushing my teeth, I felt that I looked very tired today.

A good strategy for Mandarin is:

• first identify the time/background phrase
• then find the main verb
• then identify the content of that verb

Here:

• time/background: 站在镜子前刷牙的时候
• main verb: 觉得
• content: 自己今天看起来很累

Yes, but the meaning changes slightly.

• 觉得 = felt / thought
• 发现 = discovered / noticed / realized

So:

• 我站在镜子前刷牙的时候，觉得自己今天看起来很累。 = When I was brushing my teeth in front of the mirror, I felt I looked tired today.

• 我站在镜子前刷牙的时候，发现自己今天看起来很累。 = When I was brushing my teeth in front of the mirror, I noticed/realized I looked tired today.

发现 sounds a bit more like noticing a fact.
觉得 sounds more like a personal impression.

Both can work, but 觉得 is softer and more subjective.

Yes, 刷牙 literally means brush teeth.

Chinese often omits possessive words like my, your, or his when they are obvious from context.

So:

• 我刷牙 = I brush my teeth
• 他洗脸 = he washes his face
• 她闭上眼睛 = she closes her eyes

Since the subject is clear, Chinese usually does not need to say 我的牙.

This is very common with body parts and routine personal actions.