It follows the same rules with saving and investing to ensure a good retirement. The FIRE movement is based upon investing enough to be financially independent. We usually use the 4% rule to determine a safe withdrawal rate.
We allow compounding interest to work to make our money grow to the point where we no longer have to work.
Compounding interest is the interest upon interest. As your assets gain more money, it will grow larger like a snowball rolling down a hit.