Changing air filters in your central heating and air conditioning system can be a real task. It is the fact of remembering to do it. I used to be very forgetful on this and then I learned something. Your central heating and air conditioning system will give you more or less a sign when it is overdue time to change the air filter in the central heat and a/c unit. You will either hear a kind of rumble noise coming from your heat and a/c unit itself. This means that it is starting to work overtime to heat or cool your home. If you address it right away, there is no harm done in this. That is sometimes what alerts me that it is time to change the air filter and that I forgot. But really what I like to do if I remember to each month is mark a certain day on my calendar to when to change the air filter of my central heating and air conditioning system unit. That way when I look at it, I know the exact day and it will remind me. Changing your air filter to your central heating and air conditioning system is something that only takes a few minutes of your time. It is something that there should be no excuse on not doing unless you have some issue getting to the air filter in order to change it. Which believe it or not, I knew someone once who had that problem. But other than that, look for the signs or mark the calendar.