Examine the phrase or sentence you've written or plan to write. Pay close attention to the sentence structure and how minutes will be used in the sentence.
Determine whether you're using the number of minutes as an adjective to describe a noun. If so, hyphenate. For example, "Lisa took a 30-minute jog" is hyphenated between the number and minute measurement because it specifically describes the duration of Lisa's jog.
Refrain from hyphenating the number of minutes if they're not modifying the noun. For example, you wouldn't hyphenate "Lisa's jog lasted 30 minutes" because in this case, "30 minutes" isn't an adjective.