Learn Italian: Noi siamo stanchi, ma ci sforziamo di completare questa impresa epica. - We are tired, but we force ourselves to complete this epic feat.

The verb here is sforzarsi, a pronominal verb meaning to force oneself or to make an effort. The ci is the reflexive pronoun for noi (we), so it literally means we force ourselves.

Why do we need the preposition di before completare?

In Italian, many verbs of effort or attempt require the preposition di to link them to a following infinitive verb. Just as you say cercare di (to try to), you must use di after sforzarsi to introduce the action you are struggling to achieve.

I usually see impresa translated as company or business. Why does it mean feat in this sentence?

The noun impresa literally translates to an undertaking or enterprise. While it is frequently used in modern Italian to mean a commercial business, in a descriptive context like this—especially when paired with epica—it refers to a grand undertaking, quest, or feat.

Could we drop the subject pronoun Noi at the start of the sentence?

Yes, you could simply say siamo stanchi. Since Italian verb endings already indicate who is acting, subject pronouns are usually dropped. Including Noi here adds deliberate emphasis to our specific struggle and sets up a strong contrast for the effort we are about to make.