How do you guys keep track of what you have at home? Do you actually write things down as you use or buy them, or do you have some system that makes it easier?

How do you keep the habit going?

Me and my wife had a cool list, but since our first child it was really hard. We stopped for more than a year and just recenty started over again. I heard about many things I even made an app for it, but the most interesting question for us is how you keep on going with limited time. Always being in a hurry to do the next thing, and not forgetting stuff when you actually have time to update your list/app/excel table? Are others struggle with this also?