How did you tighten excess skin after fat loss?

Meaning your answer is, you were lucky, didn't need to do anything?!?!

We all know fat doesn't convert to muscle, maybe shrinks, leaving loose skin which if bulking muscle into, probably won't be the body shape desired. Hope someone has other results.

Not implying that it is impossible but OK, I'm dense. Where does the loose skin go, or how to tighten, reduce the sag? Huge muscles under a lot of skin might not even be seen.