I don't really believe in fortune-telling, because I don't believe but often use it to enjoy something like choosing lunch.

I like to be fun as much fun as I can.

I don't really believe in fortune-telling, because I don't believe but I often use it to enjoy something like choosing lunch.

You seem to repeat yourself here: "I don't really believe in it, because I don't believe

I like to bhave fun as much as I can.

I like to have fun as much as I can.
OR
I like to be as fun as I can.

I don't really believe in fortune-telling, because I don't believe but often use it to enjoyI but often use it, just for fun, for something like choosing lunch.

I'm not sure if I missed something, but it seemed that you were repeating the not believing in fortune telling, so I deleted the 2nd one.

I like to be fun as much as I can.

A smoother expression would be "I like to have as much fun as I can"