If you want a quick rule for search intent—the kind people look for when they type this phrase into a browser—the answer is: use it when you believe something lacks the energy, resources, or capability to work.
It works best when there’s a visible gap between what was promised and what’s happening. That gap could be performance, motivation, or momentum.
When people say it about a person, they’re usually judging effort or readiness. When they say it about a plan, they’re usually judging feasibility or momentum. When they say it about a device or system, they’re usually judging operational power.
