In the early days of his blog, Cal Newport included affiliate links in all book recommendations. The idea was for these to bring in enough Amazon points for him never to have to use his own money when shopping for books.
Sometime later, as he started working on his first book, he imagined walking into any bookstore and being able to find his own books on a shelf.
More recently, having three young children at home, he realised there was no way everyone would remain quiet while he recorded the first episodes of his podcast. He knew he needed a dedicated space and was interested to see if what the podcast made could cover the rent within a year.
Each of these goals was SMART but more importantly, Cal designed them to be a continued source of joy for weeks and months after completion. This secret ingredient steered him away from always only focusing on what's next.
Knowing why you want to get somewhere also makes it easier to stop. In Quit, Annie Duke explains the importance of setting clear kill criteria for any venture. Defining them upfront helps minimise biases like the sunk cost fallacy.