I believe in gravity because if I let go of a ball it falls to the ground.

I believe the sun is coming up tomorrow because it always comes up every morning.

I believe that we are on a rock spinning around a sun because I've seen sci fi movies.

The thing about these beliefs is that I become less sure as I go down the list. The idea of attributing characteristics to something that has no evidence at all of existince is alien to me outwith creative writing.

Useful beliefs could be something like... I believe I'll achieve all my goals and come up with newer even better goals in the future.