Quick: what did you have to eat last week Thursday? And I mean everything. Every drink, snack, meal, and mouthful throughout the entire day. Chances are, you can't recall, and that's fine...unless you're trying to analyze problems with your current dietary habits and improve upon them.
Tracking everything you eat is the only reliable way to detect unhealthy patterns and measure your progress in correcting them. (The same is true for fitness, but that's another story.)
But there's more to it than that.
The venerable pushup has long been a staple of exercise routines and for good reason. It's easy to do most anywhere (do not try them in pools of molten lava) and provides a good workout to the triceps, shoulders, chest, and core stabilization muscles. There are also hundreds of variations of the pushup, most to make it harder or work some part of the body more intensely, and some to make the movement easier for those not quite ready to do the real thing.
