Sometimes a full page to-do list is just too much. Because you are tired or hormonal or angry at your spouse or it's raining outside. You just don't have it in you to tackle that looong list of stuff that needs doing. Looking at it depresses you.
Yet there's still stuff that needs doing.
That's when the half page to-do list comes in handy. Take a normal sheet of paper that you use, and literally fold it in half. Then write your bare bones, have-to-do-this-or-the-world-will-stop, list on that half page. Write the other stuff on a longer list another day. A day when you have more energy, more happy, more motivation. But don't beat yourself up about the half page days. We all have em.
(For you techie types who have all this on electronic gadgets, just ignore this advice-- this will not apply to you. I still love paper, paper, paper. I realize that makes me backwards and I fully accept that. Embrace it, in fact.)