Most critters including humans get their get-up-and-go from the stuff they eat and drink. And they get stuff to eat and drink by using their get-up-and-go (to hunt or fish, harvest crops, stroll to the nearest McDonalds, etc).
Scientists say you can’t make new get-up-and-go or get rid of old get-up-and-go. You can only change get-up-and-go into a different form of get-up-and-go, or into stuff.
Likewise, they say you can change stuff into other stuff or into get-up-and-go. But you can’t make new stuff and you can't destroy existing stuff.
(For example, you can’t get rid of a McDonalds burger, you can only change it into shit. No, hang on, it’s shit in the first place. Better example needed).