این هفته اصلا ورزش نکرده ام، اما بعد از کار به پارک میروم.

In Persian, the verb usually shows the subject, so the pronoun is often omitted.

• نکرده‌ام = I have not done
• می‌روم = I go / I am going

Because the -ام ending in نکرده‌ام and the -م ending in می‌روم already show I, you do not need to say من unless you want emphasis.

So:

• من این هفته اصلاً ورزش نکرده‌ام = I haven’t exercised at all this week
• این هفته اصلاً ورزش نکرده‌ام = same meaning, just less emphatic

Persian often expresses actions with a noun + کردن structure.

Here:

• ورزش = exercise, sport
• ورزش کردن = to exercise

This is very common in Persian. Similar examples:

• کار کردن = to work
• فکر کردن = to think
• استراحت کردن = to rest

So ورزش نکرده‌ام literally means I have not done exercise, but naturally it means I haven’t exercised.

نکرده‌ام is the negative present perfect form of کردن.

Breakdown:

• نـ = negative marker
• کرده = past participle, done
• ام = I am / I have ending

So:

• کرده‌ام = I have done
• نکرده‌ام = I have not done

In this sentence:

• ورزش نکرده‌ام = I haven’t exercised

A very important writing note: it is most standard to write this as نکرده‌ام with a half-space, though you may also see نکرده ام in less careful writing.

The sentence is mixing two different ideas:

1. این هفته اصلاً ورزش نکرده‌ام

   • I haven’t exercised at all this week
   • This uses the present perfect, because it refers to a period that is still connected to the present: this week

2. اما بعد از کار به پارک می‌روم

   • but I go / I’m going to the park after work
   • This uses the present stem with می-, which can express:
     • a habitual action: I go to the park after work
     • or sometimes a near-future meaning depending on context: I’m going to the park after work

So the tense change is normal. The first clause talks about what has not happened so far this week; the second clause talks about a usual or intended action.

Here اصلاً means at all or not at all when used with a negative verb.

So:

• اصلاً ورزش نکرده‌ام = I haven’t exercised at all

It adds emphasis.

You may see it written in two ways:

• اصلاً = more formal/orthographically complete
• اصلا = very common in everyday writing

Both are widely understood.

Yes, ولی could be used here.

• اما = but
• ولی = but

In many everyday contexts they are interchangeable.

So these are both fine:

• این هفته اصلاً ورزش نکرده‌ام، اما بعد از کار به پارک می‌روم.
• این هفته اصلاً ورزش نکرده‌ام، ولی بعد از کار به پارک می‌روم.

A rough tendency:

• اما can sound a bit more written or formal
• ولی is very common in speech

به is a preposition that often means to.

Here:

• به پارک می‌روم = I go to the park

So:

• به = to
• پارک = park

Without به, the sentence would sound wrong in standard Persian for this meaning.

Persian usually follows Subject – Object/Complements – Verb order, so the verb often comes at the end.

English:

• I haven’t exercised at all this week, but I go to the park after work.

Persian:

• این هفته اصلاً ورزش نکرده‌ام، اما بعد از کار به پارک می‌روم.

Notice especially the second clause:

• بعد از کار = after work
• به پارک = to the park
• می‌روم = I go

So Persian naturally puts the verb last:

• after work + to the park + I go

بعد از کار means after work.

Breakdown:

• بعد از = after
• کار = work

Persian does not use the in the same way English does. Very often, nouns appear without any article at all.

So:

• بعد از کار can mean after work
• به پارک can mean to the park or to a park, depending on context

Persian relies more on context than English for definiteness.

را marks a specific direct object, but there is no direct object here that needs it.

In the first clause:

• ورزش کردن is a compound verb
• ورزش is part of the verb expression, not a normal direct object in the same way as, for example, کتاب را خواندم (I read the book)

In the second clause:

• به پارک is a prepositional phrase (to the park), not a direct object

So there is no place here where را is needed.

It can mean either one, depending on context.

می‌روم is the present/imperfective form of رفتن (to go). In real usage it can express:

• a habit: I go
• a near future or current plan: I’m going

So:

• بعد از کار به پارک می‌روم could mean
  I go to the park after work
  or
  I’m going to the park after work

If the speaker is talking about routine, it sounds habitual. If the speaker is talking about today’s plan, it can sound future-like.

These are different writing styles for the same word.

Most standard modern spelling prefers:

• می‌روم

This uses a half-space between می and the verb.

You may also see:

• میروم
• می روم

These are common in informal typing or older habits, but می‌روم is usually considered the best standard form.

The same thing applies to:

• نکرده‌ام rather than نکرده ام

Yes, it is still natural.

The contrast is:

• I haven’t exercised at all this week
• but I go / I’m going to the park after work

This can imply several things:

• going to the park is not necessarily for exercise
• the speaker is going there to relax, walk, meet someone, or start being more active
• the speaker is contrasting formal exercise with simply going to the park

So the sentence is grammatically natural, even if the real-world meaning depends on context.