The list can be a simple as reading a book you've thought about reading.
Don't let the need for a little sacrifice and discipline keep you from attempting that list.
It's your journey.
Or what if writing a book is on the list? How would you approach it?
If you write every evening after your day job in order to craft that story, you're sacrificing time that you could use in other ways, and it takes discipline. But it can be temporary sacrifice and discipline.
If you write 300 words a day for six months you'll have enough words for a book manuscript. That's about a page and a half if you use a computer, even with good-sized margins. (Tip: Start at the point where the plot starts. Have something happen, and it leads to something else which leads to something else...)
So if you've always thought about writing a book, and you discipline yourself for six months, you can check it off your Maybe Do Someday list, and you can think about another thing on the Maybe Do Someday and spend six months preparing for it. It might take a temporary job to save the money or an agreement with the other people in your life.
Consider the event, and how much closer you would get if you just spent a little bit of time preparing for it or working toward it every day for six months.
Adding a few journeys in your life might lead you somewhere interesting that you can't even see right now. You might be creating a A Fun and Finished! list or even an Ain't Never Going To Do That Again list.
We don't generally hear about other peoples' failed lists, but having a few of those in your memory might mean you're on the right journey.