Beliefs are the Map
Beliefs describe what you consider to be reality to you. Though it is not necessarily so. Just as a map is a representation of a territory, and not the territory itself, so too are beliefs a representation of reality and not necessarily reality itself.
Say you believe that there are “no free lunches”. Is that true? Always? Say I bought you lunch just to treat you and expected nothing in return, would that belief still be true? You would certainly strive to make it true, and may succeed. The point is that it is only a representation of what you believe is reality, and not reality itself.
No one would attempt a journey to a new place with an outdated map, unless they wanted to get lost. Why would you go through life with outdated beliefs? Beliefs, like maps, need to be updated constantly if we want them to be good guides.