Questions & Answers about Sei leise, ich bin am Zielen!
I thought German didn't have an "-ing" tense. How does am Zielen work here?
Standard German usually doesn't have an exact equivalent to the English "-ing" form, but colloquial spoken German does! It is called the am-Progressiv. You form it with a conjugated form of sein (here, bin) + am + a nominalized infinitive (Zielen). It heavily emphasizes that an action is happening right at this very second.
Why is Zielen capitalized? Isn't it a verb?
Because it follows the preposition am (which is a contraction of an dem), the verb zielen (to aim) has been turned into a noun. This is called nominalization. In German, all infinitives can be used as neuter nouns, and just like all other nouns, they must be capitalized.
Could I say beim Zielen instead of am Zielen?
Yes, you could say ich bin beim Zielen. While am is the most classic way to form this colloquial progressive structure, beim is also perfectly valid and frequently used with nominalized verbs to express that you are currently deeply involved in an activity.
Why does the sentence start with Sei?
Sei is the informal singular (du) command (imperative) form of the verb sein (to be). Because sein is completely irregular, its imperative doesn't follow the standard rule of just dropping the ending from the present tense conjugation.