Arjuna reinforces his body to be less scrawny

Naturally the reason your ambushes failed was because you were a scrawny wimp before. This, you decide, cannot be allowed to stand. You already have the means and capabilities to train yourself to amazing heights in short periods of time-remember what happened when you merely played around when fully Reinforcing your body? You developed new muscles literally overnight!-and it's about time you put these capabilities to use.

And to use these capabilities go, making your body develop and strengthen in a single week to levels that other humans take months or years to achieve. Sure you have to almost literally eat your own body weight in food multiple times per day that week, but by the end of it...okay, you're still a scrawny shrimp, but you're a scrawny shrimp whose made of solid steel. Your muscles are tougher than dad's for pete's sake! You can lift the couch with ease even when you're not Reinforced, run from one side of the city to the other and back at a sprinter's pace, and have dexterity and reaction times equivalent to your utterly amazing body.

Maybe this was what it was like for ancient humans compared to modern humanity?