When you find yourself bored or uninterested, you can use a variety of synonyms for the phrase "be dull." Some options include "lackluster," "mundane," "tedious," "unstimulating," "tiresome," "dreary," and "humdrum." All of these words convey the same general idea of a lack of excitement or interest. If you want to describe a person who is uninteresting, you might use the words "bland," "flat," or "insipid." Alternatively, you could use phrases like "fail to capture your attention," "lack sparkle," or "fall flat." Overall, there are many ways to express the concept of something being dull or boring, allowing you to add variety and nuance to your writing or conversation.