For any character you are already working with, write a single sentence that describes their entire life to date. Then write a paragraph that does the same. Next, write a sentence and a paragraph that covers a particular decade of their life. Next, tackle a single season. Next, a month within that season. Next, a day within that month. Finally go down to a minute. Feel free to skip any of these time periods that don't interest you and/or, tailor the time frames and substitute different ones, say seven years, a fortnight or a weekend to suit the needs of what you’re writing.
Consider adding more specific length constraints to what you write, beyond just the sentence and paragraph — perhaps 20 words for the sentence and 150 words for the paragraph. As always, adapt the prompt as needed to make it work for your text.
Good writing.