yojeum nae cheryeogi jeongmal johajyeosseo.

요즘 means these days, lately, or nowadays. It sets the time frame for the whole sentence, so it often comes near the beginning.

In Korean, time expressions are commonly placed early in the sentence:

• 요즘 내 체력이 정말 좋아졌어.
• 내 체력이 요즘 정말 좋아졌어.

Both are possible, but putting 요즘 first sounds very natural.

내 means my. It comes from 나의, which is the full possessive form of 나 (I / me).

So:

• 나 = I / me
• 나의 = my
• 내 = my (shortened, very common)

In everyday speech, 내 is much more natural than 나의 here.

체력 means physical strength, stamina, or endurance. It usually refers to how much energy your body has, especially for physical activity.

It is not exactly the same as:

• 건강 = health in general
• 힘 = strength/power
• 기운 = energy/spirit

So if someone says 체력이 좋아졌어, they usually mean their body can handle more activity, exercise, work, or daily life than before.

The 이 is the subject marker.

• 체력 ends in a consonant, so it takes 이
• If a noun ends in a vowel, it takes 가

So:

• 체력 + 이 → 체력이

This marks 체력 as the subject: the thing that has improved.

Yes, but the nuance changes.

• 체력이 정말 좋아졌어: focuses on the fact that your stamina has improved
• 체력은 정말 좋아졌어: marks stamina as the topic, often with a contrastive feeling

For example, 체력은 좋아졌어 could suggest:

• my stamina improved, but maybe something else did not

In a simple neutral statement, 체력이 sounds very natural.

좋아졌어 comes from:

• 좋다 = to be good
• 좋아지다 = to become good / to get better
• 좋아졌어 = became better / got better / has improved

Breakdown:

• 좋- = the root from 좋다
• -아지다 = to become
• -었어 = past tense in casual speech

So 좋아졌어 does not just mean was good. It means there was a change: it became better than before.

Because 좋아졌어 emphasizes improvement or change over time.

Compare:

• 좋았어 = was good
• 좋아졌어 = got better / improved

If you say 요즘 내 체력이 정말 좋아졌어, you are saying your stamina is better now than it used to be.

If you said 요즘 내 체력이 정말 좋았어, it would sound less natural in this situation because it just describes a past state rather than a change.

정말 means really or truly. It strengthens the statement.

So:

• 내 체력이 좋아졌어 = my stamina improved
• 내 체력이 정말 좋아졌어 = my stamina really improved

It adds emphasis and makes the speaker sound more certain or impressed.

좋아졌어 is casual, informal speech. It is used with:

• friends
• family
• people younger than you
• people you are close to

More polite versions would be:

• 요즘 제 체력이 정말 좋아졌어요. = standard polite
• 요즘 제 체력이 정말 좋아졌습니다. = formal

Also note:

• 내 is casual
• 제 is the humble/polite form of my

It can be left out if the meaning is clear from context.

For example:

• 요즘 체력이 정말 좋아졌어.

This is very natural in Korean, because Korean often omits words like my, I, or you when they are obvious.

Using 내 is also fine. It just makes the subject more explicit.

A very natural polite version is:

• 요즘 제 체력이 정말 좋아졌어요.

Changes:

• 내 → 제 for polite my
• 좋아졌어 → 좋아졌어요 for polite ending

If you want to stay polite but not use the humble 제, you may also hear:

• 요즘 체력이 정말 좋아졌어요.

This is common because Korean often drops possessives when they are understood.

It is pronounced approximately as 체려기.

That happens because of sound linking:

• 체력
  • 이
• the final ㄱ sound links to the next syllable starting with 이

So:

• 체력이 → 체려기

You do not need to change the spelling, only the pronunciation.

It can be used for both.

You can say it if:

• you can exercise longer than before
• you do not get tired as easily
• you can work or study with more energy
• your body feels stronger in daily life

So 체력이 좋아졌어 is broader than just I got better at sports. It means your physical endurance or stamina has improved in general.