Jeff went to bed and tried to fall asleep. Sadly he have failed miserably, since that was the case he wrote a message that |he has a splitting headache and feels ill and won't be able to come to work tommorow|.
Jeff wasn't an idiot so when he started typing commands into his [Creator of Flesh] ability. He started with cardiovuscular system then improved his respiratory system, nervous system, digestive system and last but not least was upgrades to his organs.
Someone would ask why he didn't upgrade his skin to unpenetrable by anything or something? Simple Jeff needs to have at least basic understanding on how these changes would work and also his veins could pop if he scheduled massive overhaul of his body from "material exhaustion".<*>
Jeff knew how he could upgrade everything even an idiot would now this. Upgrade materials he commanded to make his arteries from mix of iron, bonematter and normal material from which veins are made from, but with reinforced structure. <**>
Normal veins only had their structure reinforced.
Now some might ask how and why would you add iron and bones to the arteries? Bones could be added by shoving them near the other bones which will also reinforce the other ones, why iron? Even simpler it's just because our daily diet already has quite big amount of iron in it, remmeber why your blood is red? Yeah same principle, Jeff would only need to eat a little more spinach.
Respiratory system was a little tricky so Jeff only deleted some unnecesarry turns here and there and made the "air pipe" as short as possible while increasing his lung capacity by adding extra alveoli on already existing "branches" and improving air ways between said branches. Also he increased the number of these and perfected his nose and mouth a little. Not because he wanted them to look nice no, he only made them with intention to make air flow easier through them without affecting ability to swallow food too much.
His nervous system was propably the easiet since we feel pain and othe things through little zaps to our brains from respective nervs. Jeff commanded them to be made from a little more exotic matterials like gold, of course he knew he needed to upgrade his digestive system so it would be able to digest gold. Also he decreased density of nervs in some areas and increase them in others. Why? Who didn't stub their toes on furniture of course we don't need that many ners in there. Fingers on th other hand could use more of them to make them more dexterous, of course it won't be substantial change for anything bigger Jeff would need to have any muscles in them. <***>
The digestive sytem was very simple, Jeff watched a video on youtube about stomach acid and how to make it more potent and he just commanded his stomach to make this kind of acid while making other compound that neutralise this acid to prevent his stomach from digesting itself. He also added additional intestine that would collect and store hard to digest things and would over long time would be digested inside new dead end intestine. Others already existing intestines were shortened to make place for a new one and shaped so that HDF<****> would fall into new one easily. He also placed some beacons for bacteria that usually works on HDF.
Jeff was racking his brain so hard that he developed splitting headache and had to stop improvmets. He clicked [Confirm] option under his commands and went straight to bed.