Commence
The first step he was to take now that he had already entered his training phase was to begin training his body to produce an excess of myostatin to counter the Herenal Virus when he infected his body with it. Myostatin limited muscle growth, thus training his body to produce an excess of it to counter the virus that consumed the protein was necessary to maintain his natural physique when he wasn't using Hypertrophic Surge.
The best way to do this was to simply train his body to be able to counter the virus in his body. Specifically, training it to produce excess myostatin to counter the shortage of myostatin caused by the virus. Only when the excess canceled out the shortage would his body be able to maintain its natural physique.