The thing about writing an invoice is that invoices typically reflect actual work that has been done, services provided, or items taken off a shelf.
Too bad an invoice can't be more like a best-selling novel or even a movie about a government cover up with aliens and a cute local bartender played by Sandra Bullock where she's down on her luck and poor but she has always been fascinated by molecular biology and she uses this knowledge to help the handsome thirty-something FBI agent who is single and who is sick of putting up with all the crap from his supervisors. Together they prevent an alien invasion using Bullock's radical theories on DNA. The movie ends at the bottom of an abandoned mine shaft where they kiss for the first time.
Invoices aren't like that though. They're just pieces of paper that say "I did something, pay me."
Writing invoices . . . eh.