I want to disagree with Michi on precisely the example he brings up—the law of the state. Most human beings, maybe even all of them, are emotionally moved by “the law” because they feel something toward the state. Usually this is a mixture of different emotions (not always conscious or clearly sorted out): fear, sympathy, respect, aversion, etc. Of course, I’m not making the factual claim that this “emotional response” is enough by itself to motivate them to act, and I’m not even claiming that it is the main thing.
If I’m right about the law of the state, then all the more so regarding the service of God.

I’ll just note that the questioner wasn’t really speaking on the evaluative plane (how one ought to serve God), but mainly raised a factual claim (and in my opinion a correct one), that human beings also rely on their emotions in this matter.
And here I’d suggest a simple thought experiment to Michi himself: try to imagine your extensive intellectual involvement in matters of Judaism without the emotion you have toward it. Can you actually do that?

You’re returning to the instrumental plane. I commented on that, and from my point of view it isn’t very interesting.

If by “instrumental” you mean an attempt to ground the service of God in emotion rather than in value, then I’m with you (although in my opinion that wasn’t what you were asked). But according to what you’re saying, religious emotion is not a must. If that is your position, then it’s a caricature of religion or of the service of God in general. There is no such thing. To the extent that we can even assess what God wants from us, it is highly unlikely that He equipped us with emotion and did not expect us to make use of it in this matter. Therefore, in that sense, the emotional element is essential to the service of God, not instrumental.

Rabbi, I do not see any realism in a life of Torah and commandments without some feeling of love
toward the religious way of life, or at least toward part of it.
And the comparison to the laws of the state is also not correct in my opinion.
After all, most people obey the laws of the state because they are afraid of punishment.
But nowadays there is no physical punishment, and most of us also do not feel the spiritual punishment / the loss that we incur through it,
if we are not connected in our hearts to the life of Torah.
And in the end we were commanded:
“And you shall love the Lord your God with all your heart and with all your soul and with all your might.”
So what is the difference between these things and your claim
that emotion has no intrinsic significance in the service of God?
This is just empty chatter.

You are confusing the psychological reason for obeying the law with the essential reason. I am dealing not with the question of why people obey the law, but why it is proper to do so.
As for emotions and their status, I explained that here in several columns. You are welcome to search and read my empty chatter there.

Why is it proper to obey state laws that have no logical reason?

Search here on the site for “the categorical imperative,” and you’ll find explanations.

If you kept the law only because of the logic in it, that would not be commitment to the law.