How do I say that one thing is another using active voice?

I've tried typing this question or variations of this question into Google to no avail, so I apologize if it has already been answered elsewhere. I'm trying to edit a paper for a class in which the instructor has written the following:

I know that [to be verbs] CAN have the proper place, so don't think me a tyrant. But since one of the major goals of this class is to get your [sic] to write at this high level, I want you to strive to write without any use of the TO BE verb in your independent clauses.

In this particular case, the entire sentence is "The American man is a proud man." Perhaps not the greatest sentence, but it is setting up a point later in the paragraph. The only verb in the entire sentence is "is," and I feel like, even though it is technically a to-be verb, it is not being used as an auxiliary or helping verb and, thus, must be active? The man is actively being proud.

The sentence could be somewhat rewritten as "The American man exists in a perpetual state of proudness," etc., but, aside from somewhat altering the meaning that the author is trying to get across, it feels a lot like wordiness for wordiness's sake.

Is it best to simply eliminate the sentence altogether in this context, or can anyone think of a way to reword this and make it "active voice" (which, to the professor, apparently just means no to-be verbs) without completely losing the meaning/clarity?

E-Prime, or English-Prime, constitutes an exercise in writing/speaking English without using any form of the verb "to be". For instance, in place of saying "The American man is proud," one might write "The American man feels proud," or "The American man tends to stay proud," or as Xanne above says, "takes pride", all active verbs.