Learn Hardcore Russian: Вечером я открываю ежедневник и читаю то, что я написал, чтобы понять, как меняется моё самочувствие. - In the evening I open the planner and read what I wrote in order to understand how my well-being is changing.

Why is открываю / читаю in the present tense if this is something I do regularly (every evening)? In English I would say “I open / I read” too, but is that the same idea?

Yes, it’s basically the same idea.

In Russian, the present tense is also used for:

Actions happening right now
Actions that are habitual / repeated (like “every evening”)

So:

Вечером я открываю ежедневник…
= In the evenings / In the evening I (usually) open my planner…

The word вечером (“in the evening”) supplies the idea of time/repetition, and the present tense verbs (открываю, читаю) naturally express a regular habit, just like English “I open, I read” in “Every night I read before bed.”

Why is it ежедневник and not дневник? Don’t both mean “diary”?

They are related but not the same:

дневник
- General word: can mean diary (personal journal), or school record book (grades, homework), or sometimes log/journal.
- More emotional / personal when used as “dear diary”.
ежедневник
- More specifically a daily planner / organizer.
- Used for notes, schedules, plans rather than emotional confessions.
- From каждый день / ежедневно (“every day”).

In this sentence, ежедневник suggests a planner or log where you track things (like your well‑being), not a teenage “dear diary” type journal.

Why do we need то, что? Could we just say …и читаю, что я написал…?

You can say:

…и читаю, что я написал…

This is grammatically correct and sounds natural.

But то, что is a very common structure:

то = “that/what (thing)”
что = “which / that” (relative pronoun)

Together то, что works like English:

“that which…”
“what(ever) …”

So:

читаю то, что я написал
≈ “I read that which I wrote / what I wrote.”

The то emphasizes “the thing(s)” written. Without то, the focus is more simply on the action: “I read what I wrote.” Both are fine; то, что is a bit more explicit and formal‑neutral.

Why is there a comma before что in читаю то, что я написал?

Because что я написал is a subordinate clause (a dependent clause), explaining what you read.

Russian punctuation rule:

A relative clause introduced by что, который etc. is normally separated by a comma from the main clause.

Structure here:

Main part: я … читаю то
Subordinate clause: что я написал

So you must write:

…читаю то, что я написал… ✔️

Why is it я написал (perfective past) and not я писал?

Aspect matters here.

написал (perfective) = finished writing, result is complete.
писал (imperfective) = was writing / used to write (focus on the process or repeated action, not the finished result).

You are reading what is already written in the notebook, so the result is important. That’s why perfective is used:

то, что я написал
= “that which I have written / what I (have) written (down).”

Писал here would sound unfinished, like emphasizing “I was in the process of writing,” which doesn’t fit reading finished entries.

How does чтобы понять work? Could I say для понимать or something like that?

You cannot say для понимать. That is incorrect.

For purpose / “in order to…”, Russian usually uses:

чтобы + infinitive

So:

чтобы понять = “in order to understand”
чтобы купить билеты, я пришёл пораньше — “I came early to buy tickets.”

Для + noun is used when the “goal” is a thing or noun, not an action:

для понимания — “for (the) understanding / for understanding” (noun)
для отдыха — “for rest”

But if you want “to understand” as a verb, it must be:

чтобы понять, not для понимать.

Why is the verb меняется reflexive (with -ся)?

Меняется is the reflexive form of менять(ся).

менять что-то = “to change something” (transitive)
- Он меняет работу. — “He is changing jobs.”
меняться = “to change (oneself); to change / to be changing” (intransitive, subject changes)

Here:

как меняется моё самочувствие
= “how my well‑being changes”

Your самочувствие is not changing something else; it itself is changing. That’s why the reflexive form меняется is used.

Why is it моё самочувствие and not мой самочувствие?

Because of gender agreement.

самочувствие is a neuter noun (ends in -е but behaves like здание, море, счастье).
The possessive pronoun мой must agree with the gender and number of the noun:
- мой (masculine): мой друг, мой стол
- моя (feminine): моя книга, моя сестра
- моё (neuter): моё окно, моё счастье, моё самочувствие
- мои (plural): мои друзья

So neuter noun → моё самочувствие.

Could I omit я in то, что я написал and say то, что написал?

Yes, you can say:

читаю то, что написал

This is understandable and can sound a bit more colloquial / compact.

However:

то, что я написал is more explicit, neutral, and slightly clearer, especially in writing, because it clearly states who wrote it.
то, что написал relies on context; it could theoretically be “what (someone) wrote” in general if context isn’t clear.

In this sentence about my own planner, both versions are OK, but the version with я is stylistically safer and clearer.

Why is it вечером and not something like по вечерам? What is the nuance?

Both are possible but slightly different in nuance:

вечером
- Literally “in the evening” (instrumental singular).
- Can refer to this evening or to a general routine, depending on context.
- Here, in context, it means “(usually) in the evening.”
по вечерам
- More explicitly “in the evenings / on evenings (as a rule)”.
- Stronger sense of regular, repeated habit.

So:

Вечером я открываю ежедневник…
= Often feels like “In the evening I (usually) open my planner…”
По вечерам я открываю ежедневник…
= “In the evenings I open my planner…” (clearly habitual, recurring)

The sentence as given is natural; вечером can absolutely express a routine.

Why are there so many commas: before что, before чтобы, and before как?

Each comma separates a subordinate clause from the main clause. Let’s mark them:

Вечером я открываю ежедневник и читаю то,
→ main clause
что я написал,
→ subordinate relative clause (what I wrote)
чтобы понять,
→ purpose clause (in order to understand)
как меняется моё самочувствие.
→ clause of “how…”, object of “understand”

Russian comma rule: almost every subordinate clause introduced by что, чтобы, как, когда, потому что etc. is separated by commas.

So the commas are obligatory:

…, что…, …, чтобы…, …, как…

Could I use как изменяется моё самочувствие instead of как меняется моё самочувствие? Is there a difference?

You could say:

…чтобы понять, как изменяется моё самочувствие.

This is grammatically correct.

Nuance:

меняться is very common, neutral, everyday: “to change”.
изменяться is often a bit more formal / bookish, and can imply a more noticeable or systematic change.

In everyday speech about how I feel, меняется sounds more natural and conversational.
Изменяется wouldn’t be wrong; it just feels slightly more formal or clinical.

What exactly does самочувствие mean? Is it just “mood”?

Not exactly.

самочувствие = overall physical and emotional state / how you feel, especially in terms of health and well‑being.

Examples:

Как твоё самочувствие?
= “How are you feeling? / How’s your health / how do you feel (physically and mentally)?”

It includes both:

physical feeling (tired, energetic, sick, healthy)
general inner state (fine, weak, unwell)

“Mood” alone is more like настроение in Russian.
Here, моё самочувствие is broader than just mood.