The personal meaning that the items in your home carry are very important to your mental health. All of our sensory experiences impact us with meaning, but none more so than our sense of sight. The minute we see things, our brain is interpreting their appearance based on any experiences we have had with the thing we are looking at. If it is a thing we have had a bad experience with, then seeing it will make us feel negative. If it is a thing we have had a good experience with, it will make us feel positive. We also interpret things visually using our subconscious. For instance, we may have never had a personal experience with the color yellow, but colors have a psychological impact simply by being colors.
The point of this is simply that people need to consider their personal connection to the items they decorate with and fill a home with because they will have a daily psychological impact on them. This is why many people choose to decorate with personal effects, such as family heirlooms, art that their kids made, favorite quotes and artistic representations of things they value. These items are directly associated with something that the decorater values, which means it has very positive personal meaning.
A person may also want to decorate with things that are less personal but still carry some kind of positive association. For instance, some people love to decorate with abstract art. There is nothing in reality that is as abstract as abstract art. Looking at it does not make us think of real life people, places or events. Instead, it brings to mind associations with concepts, emotions and states of being, which are abstract themselves. For many people, these types of associations within their personal space is more therapeutic than images of people, places or events that they are personally connected to.