Hisao despised seeing Lilly cry, as proven when she cried within Hisao's arms. A man like him definitely would not want to see his love bawl like that again.
Now knowing Emi, if she got even the slightest whiff of what happened, all it would simply take for Emi to get Hisao exercising every day would be to simply say "Do you really want to see Lilly cry like that again?" That would definitely hit home for someone such as Hisao.
Plausible too. Nurse would have gotten a report from the nearby hospital by the airport, would proceed to give a stern lecture to Hisao for his reckless act and have Emi keep an eye on being his helper. Emi loving track, will have Hisao running laps to keep fit.
Then again, I'm a Lilly-bro, so can't help but be a bit bias :3