Schuster, who will earn around $800,000 after re-signing until the end of 2027, is regarded by Manly staff as one of the most talented players to walk through the Brookvale gates in decades.
He had impressed with his training leading up to Christmas before waking up one morning itchy and covered in spots.
“Chicken pox as an adult, it can be quite dangerous and I wouldn’t wish it on anyone,” Schuster said.
“Some of our coaching staff had it as well, I don’t know if I caught it off them or gave it to them. But it’s definitely the sickest I’ve ever been.
“I was struggling with aching pains. It was the flu with shocking headaches, I couldn’t eat or drink for days.
“Coming back to training had to be really managed because my immune system was shot, I had no energy, I was dehydrated because I hadn’t had any fluids for days. It took a while to get back.
“I dropped five kilos and now I’m back and feeling good, I want to be around 110kg which is light as a back-rower.”
A spiral fracture to Schuster’s ring finger, which is still bent at the tip, required surgery to avoid a similar fate to Roosters star Angus Crichton, who had his own finger amputated after playing on through a similar injury during his teens.
“I’ll take the surgery thanks, I don’t want to cut it off,” Schuster laughed.
Schuster’s calf strain then laid him low as he completed running drills post-surgery, keeping him out of full team training until this week.
His move to the back row comes with an added defensive load and pairs him with marquee signing Luke Brooks on the left edge, though Ben Trbojevic’s impressive pre-season has him challenging for the same spot.
Brooks is more familiar than most with the brickbats Schuster has weathered throughout his 50-game career.
Manly’s new five-eighth was dubbed the next coming of Andrew Johns by sections of the media in his debut season. He was a regular punching bag throughout an 11-year Wests Tigers career that failed to yield a finals appearance.
“I’ve dealt with what he’s going through,” Brooks said. “I can relate to it, definitely. People forget how young he is. And how you deal with that outside noise, it’s not really a natural thing.
“It takes a while to learn how to live with it. It’s easier said than done. For me personally, learning how to deal with those critics came from experience and I’m happy to help him if he needs it at all.”
Sports news, results and expert commentary. Sign up for our Sport newsletter
NRL is Live and Free on Channel 9 & 9Now