Я стараюсь говорить спокойно даже тогда, когда волнуюсь.

Стараюсь is the 1st person singular present-tense form of стараться, meaning to try or to make an effort.

So:

• я стараюсь = I try / I am trying

Russian often uses the present tense of стараться to express a general habit or ongoing effort, not just something happening at this exact second.

After стараться, Russian normally uses the infinitive of the second verb.

So:

• я стараюсь говорить = I try to speak

This works like English try to do something.

Compare:

• Я говорю спокойно. = I speak calmly.
• Я стараюсь говорить спокойно. = I try to speak calmly.

Using говорю after стараюсь would be ungrammatical here.

Говорить is imperfective because the sentence describes a general way of speaking, not one completed act.

• говорить = to speak, to be speaking, to speak in general
• сказать = to say, to say once, to finish saying

Here the meaning is about maintaining a calm manner of speech, so говорить fits naturally.

If you used сказать, it would sound more like to manage to say something calmly once, which is not the idea here.

Because спокойно is an adverb, and it describes how the person speaks.

• спокойный = calm, peaceful — an adjective
• спокойно = calmly — an adverb

Since it modifies the verb говорить, Russian needs the adverb:

• говорить спокойно = to speak calmly

If you wanted to describe a person, you would use the adjective:

• Я спокойный = I am calm

Даже тогда, когда adds emphasis. It means something like:

• even when
• literally, even then, when

So:

• когда волнуюсь = when I get nervous / when I worry
• даже тогда, когда волнуюсь = even when I get nervous

Russian often uses тогда, когда to make the time relationship more explicit, and даже adds the idea that this is true in difficult situations too.

You could shorten it to даже когда волнуюсь, and that would still be natural.

It can feel redundant to an English speaker, but in Russian this is a normal structure.

• тогда = then
• когда = when

Together, тогда, когда means at the time when. In many sentences, Russian uses both parts to build a clearer or slightly more formal time expression.

So:

• даже тогда, когда волнуюсь = even at those times when I’m nervous

It is not required in every sentence, but it is perfectly natural.

Because когда волнуюсь is a subordinate clause.

Russian punctuation requires a comma before many subordinate clauses introduced by words like:

• когда = when
• если = if
• потому что = because
• что = that

So the comma marks the boundary between:

• Я стараюсь говорить спокойно даже тогда
  and
• когда волнуюсь

The dictionary form is волноваться, which is a reflexive verb ending in -ся.

Here:

• волнуюсь = I get worried / I worry / I’m nervous

This reflexive form does not always mean a literal reflexive action like wash oneself. In Russian, many verbs simply exist in a reflexive form as their normal dictionary form.

There is also волновать, but that usually means to worry someone or to agitate someone:

• Это меня волнует. = That worries me.

So:

• я волнуюсь = I am worried / nervous
• это меня волнует = this worries me

It can cover all of those depending on context.

In this sentence, волнуюсь is best understood as something like:

• I’m nervous
• I get anxious
• I worry

A native English speaker often hears волноваться in emotional situations such as stress, anxiety, concern, or nervous excitement.

So here it most naturally means that the speaker tries to stay calm when feeling nervous or anxious.

Yes, often it can.

Russian verb endings already show the subject, so:

• Я стараюсь говорить спокойно...
• Стараюсь говорить спокойно...

Both can work.

Including Я makes the subject explicit. It may sound slightly more neutral, clearer, or a bit more contrastive depending on context.

Russian does not have to state subject pronouns as often as English does.

Yes. Russian word order is flexible, though different orders may change emphasis.

The original sentence is neutral and natural:

• Я стараюсь говорить спокойно даже тогда, когда волнуюсь.

Other possible versions:

• Даже тогда, когда волнуюсь, я стараюсь говорить спокойно.
• Я даже тогда, когда волнуюсь, стараюсь говорить спокойно.

These all mean essentially the same thing, but the focus shifts slightly. The original version is a very natural default choice.

Usually it sounds like a general habit or repeated effort.

That comes from:

• стараюсь = I try
• говорить imperfective = to speak, generally
• когда волнуюсь = when I get nervous

So the sentence suggests a repeated pattern:

• whenever I’m nervous, I try to speak calmly

It does not sound like just one specific event unless context makes it specific.

Yes, but it changes the structure slightly.

• говорить спокойно = to speak calmly
• говорить спокойным голосом = to speak in a calm voice

Both are natural, but спокойно is simpler and more general.
Спокойным голосом focuses more specifically on the voice.

Both are fine.

• даже когда волнуюсь is shorter and more conversational
• даже тогда, когда волнуюсь is slightly fuller and more emphatic

The version with тогда can sound a bit more deliberate, as if the speaker is stressing that this remains true even in those moments.

So neither is wrong; it is mostly a matter of style and emphasis.