Chelsea Fagan sets herself a high bar in writing “The Financial Diet” (Henry Holt, $19): She wants to prove to people who know little about personal finance that investing is both vital and not all that difficult.

Does she deliver?

Yes, and surprisingly well. If you had to give her a grade, it would be a solid “B” because of both her supportive tone and her ability to reduce what can be fairly complicated concepts — such as how you put together a comprehensive investment plan — to easily understood bite-size pieces.

The biggest advantage Ms. Fagan, who runs a website with the same name as her book, has going for is her approach. She is a millennial writing, in colloquial language that is occasionally profane, for other millennials.

For example, in explaining why not enough of her generation understands money, she writes: “It doesn’t help that the information available about personal finance oscillates between a less fun version of your dad yelling at you about stocks and tone-deaf articles about how millennials are not buying homes. (It’s because we have billions in dollars of student debt.)” There is actually another word after the word “debt,” but it is a noun that this paper won’t publish unless it is spoken by a prominent politician.