Shredder injured him, badly. It was a miracle he was still breathing after the battle. He spent months asleep, months in which everyone tried to keep up with their lives, looking after him like he would do for all of them. And finally, after he wakes up, he starts pushing himself again to get better.

It's understandable that it's his responsibility as the oldest one and leader of them, but for God sake, he literally can't walk without a mullet. And after the Creep attacked his family, he's been pushing himself to a whole other level.

Today, after trying to spar with Raph and messing up his knee again, Leo rested under a tree, watching his brothers train with Casey and April, impotent and frustrated.