Writing a book sounds like a very intimidating task. But in reality, when you look at each individual part: write today, write tomorrow, keep writing, find an editor, find a proofreader, etc… I would argue the sum of the parts are significantly less intimidating than the whole.
On the other hand, opening a food truck sounds pretty fun and easy. But when you start to look at the licensing, insurance, regulations, economics, etc… it becomes intimidating quickly.
Maybe the difference isn’t the objective differences in difficulty, and it’s more about the preconceptions of what the parts are. Regardless of your perspective, whenever you’re faced with a task, break it down into small parts. The smaller the part, the more accurate you can get and the better sum you will discover.