Uni, ruoka ja liikunta vaikuttavat suoraan hyvinvointiini.

All three are in nominative singular:

• uni = sleep
• ruoka = food
• liikunta = (physical) exercise

They are simple base dictionary forms (no case endings, no plural), and together they form a compound subject of the sentence.

Because the subject is three items joined by ja:

Uni, ruoka ja liikunta vaikuttavat…
Sleep, food and exercise affect…

In Finnish, when you join multiple singular nouns with ja (and), the subject is logically plural, so you use 3rd person plural of the verb:

• vaikuttaa = 3rd person singular
• vaikuttavat = 3rd person plural

So the sentence is literally:
Sleep, food and exercise affect directly my well‑being.

In standard written Finnish, that is considered incorrect; you should use vaikuttavat.

In spoken Finnish, people quite often use the 3rd person singular even with a plural subject:

• Spoken / informal: Uni, ruoka ja liikunta vaikuttaa mun hyvinvointiin.
• Standard: Uni, ruoka ja liikunta vaikuttavat hyvinvointiini.

So:

• In writing → vaikuttavat
• In casual speech → vaikuttaa is very common

Vaikuttaa in this context means “to affect / to have an influence on”.

With this meaning, vaikuttaa takes the illative case (the “into / onto / to” case) for the thing that is affected:

• vaikuttaa johonkin = to affect something

Examples:

• vaikuttaa terveyteen = to affect (one’s) health
• vaikuttaa mielialaan = to affect mood
• vaikuttaa hyvinvointiin = to affect well‑being

In your sentence, hyvinvointiini is the illative form of hyvinvointi with a possessive suffix (“to my well‑being”).

Hyvinvointiini is made of three parts:

1. hyvinvointi = well‑being (dictionary form)
2. -in / -iin = illative singular (“to / into”)
3. -ni = 1st person singular possessive suffix (“my”)

So:

• hyvinvointi → hyvinvointiin = “to (the) well‑being”
• hyvinvointiin
  • -ni → hyvinvointiini = “to my well‑being”

Spelled as hyvinvointiini, but conceptually it’s:
hyvinvointi + iin + ni

This corresponds to English “my well‑being” because the verb vaikuttaa requires the illative “to my well-being.”

• hyvinvointini = “my well‑being” in the nominative (subject) or genitive (possessive of something else), depending on context.
• hyvinvointiini = “to my well‑being” in the illative.

Because vaikuttaa (to affect) needs the illative (vaikuttaa johonkin), we must use hyvinvointiini, not the bare nominative:

• Hyvinvointini on tärkeää. = My well‑being is important. (subject → nominative)
• Uni vaikuttaa hyvinvointiini. = Sleep affects my well‑being. (object of vaikuttaa → illative)

You don’t have to, because the possessive suffix -ni already carries the meaning “my”.

• hyvinvointiini = to my well‑being
• minun hyvinvointiini = to my well‑being (with an extra explicit minun)

Using both is grammatically fine and sometimes done for emphasis or clarity, but in many cases Finnish prefers just the suffix:

• Very natural: Uni, ruoka ja liikunta vaikuttavat suoraan hyvinvointiini.
• Also possible: Uni, ruoka ja liikunta vaikuttavat suoraan minun hyvinvointiini. (a bit heavier, more emphatic)

Suoraan is an adverb derived from suora (“straight”).

Here it means “directly”:

• vaikuttaa suoraan hyvinvointiini = to affect my well‑being directly

Other examples of suoraan:

• Sano se suoraan. = Say it directly / frankly.
• Lento menee suoraan Helsingistä Ouluun. = The flight goes directly from Helsinki to Oulu.

So its role is similar to English adverbs like directly, straight, straightforwardly, depending on context.

Yes. Finnish word order is relatively flexible. All of these are possible and natural, with slightly different emphasis:

• Uni, ruoka ja liikunta vaikuttavat suoraan hyvinvointiini.
• Uni, ruoka ja liikunta vaikuttavat hyvinvointiini suoraan.
• Suoraan hyvinvointiini vaikuttavat uni, ruoka ja liikunta.

The default, neutral place is usually just before the phrase it modifies:

• vaikuttavat suoraan hyvinvointiini

Moving suoraan to the very beginning or end tends to sound a bit more emphatic or stylistic.

List punctuation in Finnish is very similar to English:

• Items in a simple list are separated by commas.
• No comma is used before ja (and) or tai (or) in normal lists.

So:

• Uni, ruoka ja liikunta… = Sleep, food and exercise…

You would not normally write:

• ✗ Uni, ruoka, ja liikunta… (no “Oxford comma” in standard Finnish)

You could, but it would change the nuance and usually sound odd in this general statement.

• Uni, ruoka ja liikunta = sleep, food and exercise as general concepts.
• Unet, ruoat ja liikunnat would sound like particular instances of these things, and is not how people normally express this idea.

For generic statements about lifestyle factors, Finns almost always use the singular:

• Uni on tärkeää. = Sleep is important.
• Liikunta parantaa terveyttä. = Exercise improves health.

So the singulars here are the natural choice.

They overlap but aren’t identical:

• liikunta

  • Physical activity in general, especially for health / fitness
  • Includes things like walking, gym training, everyday movement
  • Often used in health & wellbeing contexts

• urheilu

  • Sports, often more competitive or organized activity
  • Football, ice hockey, track and field, etc.

In a sentence about well‑being like this, liikunta is the more natural and typical word.

The sentence is neutral standard Finnish:

Uni, ruoka ja liikunta vaikuttavat suoraan hyvinvointiini.

This could easily appear in:

• a health brochure
• a school textbook
• a blog post about wellness

A more colloquial spoken version might look like:

• Uni, ruoka ja liikunta vaikuttaa suoraan mun hyvinvointiin.
  
  • singular vaikuttaa
  • mun instead of minun
  • no possessive suffix, just mun hyvinvointiin

Use hyvinvointi in the illative with different possessive suffixes (or pronouns):

Singular:

• minun hyvinvointiini / hyvinvointiini = to my well‑being
• sinun hyvinvointiisi / hyvinvointiisi = to your (sg) well‑being
• hänen hyvinvointiinsa / hyvinvointiinsa = to his / her well‑being

Plural:

• meidän hyvinvointiimme / hyvinvointiimme = to our well‑being
• teidän hyvinvointiinne / hyvinvointiinne = to your (pl) well‑being
• heidän hyvinvointiinsa / hyvinvointiinsa = to their well‑being

Example sentences:

• Stressi vaikuttaa meidän hyvinvointiimme.
  Stress affects our well‑being.

• Työ ja perhe vaikuttavat hänen hyvinvointiinsa.
  Work and family affect his/her well‑being.

All follow the same pattern as vaikuttaa hyvinvointiini in your original sentence.