Das Arbeiten im Büro macht mich müde.

Working in the office makes me tired.

Breakdown of Das Arbeiten im Büro macht mich müde.

• in: in
• dem: the; (masculine or neuter, dative)
• müde: tired
• machen: to make

Questions & Answers about Das Arbeiten im Büro macht mich müde.

Why is Arbeiten capitalized here?

In German, when a verb is turned into a noun (a nominalized verb), it is capitalized.

• The base verb is arbeiten (to work).
• As a noun, it becomes das Arbeiten (the act of working).

Other examples:

• das Essen – the eating / the food (from essen)
• das Schwimmen – (the) swimming (from schwimmen)

So Arbeiten is capitalized because it is functioning as a noun, not as a verb.

What is the function of das in das Arbeiten?

Here das is the neuter definite article the, not a demonstrative that.

• das Arbeiten = the working / the act of working

When you nominalize an infinitive (arbeiten → das Arbeiten), it is almost always treated as a neuter noun and takes das:

• das Laufen (the running)
• das Rauchen (the smoking)

So das tells you:

1. This is a noun, not a verb.
2. It’s neuter, and here it’s in the nominative case as the subject.

What is the grammatical subject of the sentence?