system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we use the term "Put your back into it!" when doing so is an unsafe physical practice for lifting heavy objects?
gpt
The safety concern is when you are trying to lift things entirely with your back, as opposed to engaging your legs and core, which is healthier.

"Put your back into it" is a way to admonish people who put even less than their backs into it - whether "it" is digging, rowing, whatever. Compare someone rowing lazily with one arm and someone rowing with their entire body, back included.