Tôi cố tập mỗi sáng.

Here, cố means to try, to make an effort, or to do one’s best.

So in Tôi cố tập mỗi sáng, cố shows that the speaker is making an effort to do the action tập.

A useful comparison:

• Tôi tập mỗi sáng = I exercise every morning.
• Tôi cố tập mỗi sáng = I try to exercise every morning.

The second one suggests effort, difficulty, or determination.

They are very close.

• cố = try / make an effort
• cố gắng = try / make an effort / strive

In many situations, cố is a shorter version that sounds more conversational.
Cố gắng is fuller and often feels a little more neutral or complete.

So these are both possible:

• Tôi cố tập mỗi sáng.
• Tôi cố gắng tập mỗi sáng.

Both are understandable. The second is slightly more explicit.

Tập can mean several related things depending on context:

• to practice
• to train
• to exercise

In this sentence, it most likely means to exercise or to work out.

That is because mỗi sáng often goes naturally with daily exercise habits. If you want to make it completely clear, you can say:

• Tôi cố tập thể dục mỗi sáng.

Here, tập thể dục clearly means to exercise.

Tôi cố tập mỗi sáng is understandable, but many learners will hear more explicit versions in everyday Vietnamese, such as:

• Tôi cố gắng tập mỗi sáng.
• Tôi cố tập thể dục mỗi sáng.
• Tôi cố gắng tập thể dục mỗi sáng.

Why?

Because tập by itself can be a little broad: it could mean practicing, training, studying a skill, or exercising. Context helps, but tập thể dục is clearer if you specifically mean physical exercise.

So:

• Tôi cố tập mỗi sáng = acceptable, especially if context already makes it clear
• Tôi cố tập thể dục mỗi sáng = clearer and often more natural for exercise

Mỗi sáng means every morning or each morning.

• mỗi = each / every
• sáng = morning

So mỗi sáng expresses a repeated habit.

It does not mean this morning.
For this morning, you would usually say something like:

• sáng nay = this morning

So:

• mỗi sáng = every morning
• sáng nay = this morning

This follows a very common Vietnamese word order:

Subject + verb phrase + time expression

So:

• Tôi = subject
• cố tập = verb phrase
• mỗi sáng = time expression

That makes Tôi cố tập mỗi sáng perfectly normal.

You can also move the time phrase for emphasis:

• Mỗi sáng, tôi cố tập.

This means the same thing, but it highlights every morning a bit more.

Vietnamese does not have to mark tense the way English does.

In English, you often need forms like:

• I try
• I am trying
• I tried

In Vietnamese, time is often understood from context or from time words such as mỗi sáng.

Here, mỗi sáng already tells you this is a repeated or habitual action, so no extra tense word is necessary.

That is why Tôi cố tập mỗi sáng is complete by itself.

If you add markers, the meaning changes:

• Tôi đang cố tập mỗi sáng. = I am trying to exercise every morning.
• Tôi đã cố tập mỗi sáng. = I tried to exercise every morning.

So the original sentence is simple and natural for a general habit.

Sometimes yes, but only when the subject is already clear from context.

For example, in conversation:

• Cố tập mỗi sáng nhé. = Try to exercise every morning, okay?

Or if people already know you are talking about yourself, Vietnamese may omit the subject. But for learners, it is safer to keep Tôi until you are comfortable with context-based omission.

So:

• Tôi cố tập mỗi sáng. = clear and beginner-friendly
• Cố tập mỗi sáng. = possible in the right context, but not the same structure

The tones are:

• Tôi — no tone mark
• cố — sắc tone
• tập — nặng tone
• mỗi — hỏi tone
• sáng — sắc tone

A rough guide:

• tôi: sounds like toy but not exactly English toy
• cố: rising tone
• tập: low, short, heavy tone
• mỗi: dipping/question-like tone
• sáng: rising tone

Tone matters a lot in Vietnamese, so it is worth practicing each word separately first, then saying the full sentence smoothly.

The difference is the idea of effort.

• Tôi tập mỗi sáng = I exercise every morning.
  This sounds like a simple fact or routine.

• Tôi cố tập mỗi sáng = I try to exercise every morning.
  This suggests it may be difficult, or that the speaker is working on building the habit.

So cố adds a feeling of intention, struggle, or determination.