Perhaps, unless he did something stupid. Like tried to save somebody. Though that wouldn't count as stupid in his opinion. And as for fat and bald-- Kagami had been neither in his later years, and considering how Shisui inherited more than just the Will of Fire from his father, there was a good chance that he would end up just like his old man-- fit and with a head full of froofy hair.

He did say it was alright. The worst that could happen had already happened to Shisui; he didn't think he could be easily swayed. And he most certainly didn't want her to hold back, because that took the fun out of training and was completely besides the point of the activity. Physically, he had an extremely high tolerance for pain. Mentally, his approach to life itself made it way too easy for him to reason and shelve things away with logic. Emotionally, he was already at his lowest.

But this was Sakura, and he was sure she'd still be able to surprise him.

"Hey." He took another sip, then lowered his cup, flashing her a brilliant smile. "What makes you think you'll succeed in having me end up in hospital at the end of things, hm?" She wanted challenge? Have some challenge.

"I cannot teach you if you hold back. When we're training, I am the enemy, remember?" He paused, taking another sip before bringing the cup down to rest on the tabletop again. "Besides, it's insulting." That last bit was murmured, and he sent her a much softer smile. Gentle admonishment.