The scripture in Philippians 4:8 says, "In conclusion, my friends, fill your minds with those things that are good and that deserve praise: things that are true, noble, right, pure, lovely, and honorable." GIGO is a concept in computer science and mathematics that says that the quality of output is always determined by the quality of the input. So, for example, if a mathematical equation is improperly stated, the answer is unlikely to be correct. Similarly, if incorrect data is inputted into a program, the output is unlikely to be informative. This concept is known as “Garbage In, Garbage Out”, and it is also applicable in everyday life.
What your life is giving out or generating today is a direct product of the input it has received over time. Now, input comes in primarily through the eyes and the ears; these two are the most essential gateways of the mind. By default, the average modern human being is besieged with all sorts of unhelpful and often harmful information (visually and auditorily) from the moment you open your eyes in the morning and pick up your phone, till you retire to bed at night.
However, you have the power to control what input your mind receives by being deliberate about the input you permit your mind to receive i.e. the music you listen to, the books you read, the words you listen to, etc. You need to guard your mind and be very deliberate about what you allow in because your life will end up reflecting whatever you are ingesting. You cannot stop birds from flying over your head, but you most definitely can stop them from building nests there! Guard your mind!