Learn Hardcore Greek: Έχω όμως όρεξη για μια μικρή βόλτα, γιατί έτσι φτιάχνει η διάθεσή μου. - But I feel like a short walk, because that way my mood improves.

With food: Έχω όρεξη για πίτσα = I feel like (eating) pizza.
More generally, like in your sentence: Έχω όρεξη για μια μικρή βόλτα = I feel like going for a little walk.

So it’s not limited to food; it expresses desire or mood for an activity as well.

What does όμως mean, and why is it placed after έχω instead of at the beginning?

Όμως means roughly however, but, or though.

In Greek it can move around more than English however:

Όμως έχω όρεξη…
Έχω όμως όρεξη…

Both are correct. Putting όμως after έχω sounds natural and slightly more conversational, and it lightly emphasizes έχω όρεξη:
I do feel like a little walk, though.

So the placement is about style and rhythm, not a different meaning.

Why do we say για μια μικρή βόλτα? What is the role of για here?

Για here means for and introduces what you feel like doing or having.

With έχω όρεξη, the pattern is:

Έχω όρεξη για + [noun]

Examples:

Έχω όρεξη για καφέ. = I feel like (having) coffee.
Έχω όρεξη για ταξίδι. = I feel like a trip.

So για μια μικρή βόλτα is for a little walk, completing έχω όρεξη.

Why is it μια μικρή βόλτα and not some other form? How do μια, μικρή, and βόλτα agree?

Βόλτα is a feminine noun (η βόλτα). In Greek, the article and adjective must agree with the noun in:

Gender: feminine
Number: singular
Case: accusative (because of για)

So you get:

μια (feminine, accusative, singular article)
μικρή (feminine, accusative, singular adjective)
βόλτα (feminine, accusative, singular noun)

All three match, just like a small walk in English, but with grammatical gender and case explicitly marked.

What exactly does βόλτα mean? Is it only a walk on foot?

Βόλτα is broader than just walk: it’s any light, pleasant outing. Common uses:

A walk on foot:
- Πάμε βόλτα στο πάρκο. = Let’s go for a walk in the park.
A drive / ride:
- Πήγαμε βόλτα με το αυτοκίνητο. = We went for a drive.
A general outing:
- Βγήκαμε βόλτα στην πόλη. = We went out for a stroll / outing in the city.

In your sentence, context suggests a little walk / stroll, but the word itself is more general: a relaxed outing.

Does γιατί here mean why or because? How do I tell the difference?

Γιατί can mean both why and because, depending on context and position:

At the beginning of a question: usually why
- Γιατί δεν έρχεσαι; = Why aren’t you coming?
Introducing a reason (often after a comma): because
- … , γιατί έτσι φτιάχνει η διάθεσή μου. = …, because that’s how my mood improves.

In your sentence it clearly introduces the reason for wanting a walk, so it means because.

What does έτσι add in γιατί έτσι φτιάχνει η διάθεσή μου?

Έτσι literally means like this / in this way / so.

Here, it refers back to the small walk:

…because this way (i.e. by doing that), my mood improves.

It links the action (the walk) to the result (better mood), roughly:

…because that’s what cheers me up / that’s how my mood gets better.

Why is it φτιάχνει η διάθεσή μου and not η διάθεσή μου φτιάχνει? Is this word order normal?

Both orders are grammatically correct:

Η διάθεσή μου φτιάχνει.
Φτιάχνει η διάθεσή μου.

Greek word order is more flexible than English. Here, putting the verb first (φτιάχνει) links it tightly to έτσι:

…γιατί έτσι φτιάχνει η διάθεσή μου.
= …because in this way my mood improves.

The subject η διάθεσή μου comes after the verb, which is very natural in Greek, especially when you want to stress how something happens (because of έτσι).

What does φτιάχνει mean here? I thought φτιάχνω was to make / to fix.

Yes, φτιάχνω primarily means to make / to prepare / to fix, but it has an extended, idiomatic meaning to improve / to lift when used with διάθεση (mood):

Μου φτιάχνει τη διάθεση. = It lifts my mood / it cheers me up.
Φτιάχνει η διάθεσή μου. = My mood is improving / my mood gets better.

So here φτιάχνει is gets better / improves, not makes in the literal sense.

How is η διάθεσή μου structured, and why is the accent on διάθεσή?

Η διάθεσή μου consists of:

η – the feminine singular article (the)
διάθεσή – διάθεση (mood, disposition) with an accent showing stress
μου – the weak (clitic) possessive pronoun (my)

Μου is an enclitic, which often affects accent placement on the preceding word. With enclitics, the main word can gain an extra accent to keep the correct stress pattern, so you see διάθεσή accented on the final syllable before μου.

Functionally, you can read η διάθεσή μου as my mood, and just remember that μου behaves like a little unstressed word that attaches to the noun and influences its accent.