It's easy to use good form on push-ups... until you start to fatigue. Instinctively, we try to make it easy to keep going by sagging the hips. This effectively lightens the load and shortens the range of motion. But of course that's incredibly bad form too.
To fix it fast, simply bring one knee up to touch the same-side elbow. That puts you back into correct alignment. Now, keep that form and continue to do reps.
If you're unsure about your starting hip position, just use this same cue before beginning a set.
Eating more and training more can get you pretty far. But if you’ve stopped making progress, it’s time to reassess and do things differently. Here’s what may be putting your gains on hold.
There's an old saying that goes, "Give a man a fish and feed him for a day, but tell him about periodization, and confuse him for the rest of his life."