I like keeping things clean and tidy. I order things when they are out of place. It has become a habit. Whenever I see something out of place, I go and tidy it up. This is good for housekeeping, but I learned that leaving things out of place reminds me to do what I intended to do. I intentionally leave my dumbbells at odd angles so that I see them as I walk past. I pick them up and exercise, returning them to a different place on the floor. The result - I have started to exercise more often than I used to. This sounds like a trivial detail, but you can apply the same principle to a lot of habits.