Retiring Leeds Rhinos prop Kylie Leuluai has revealed he was diagnosed with an irregular heartbeat midway through the 2015 Super League season.
The 37-year-old played his final game as the Rhinos completed the treble by beating Wigan in the Grand Final.
The New Zealander said he considered retiring after the Challenge Cup final win over Hull KR in August.
"It has been a tough and challenging year. I really thought about it," he told the Yorkshire Evening Post.
"Having an irregular heartbeat takes 20% of the oxygen out of your blood, so it's been very tough for me physically and it has an effect mentally as well.
"That's the reason why I've been playing shorter minutes. [Head coach] Brian McDermott and the club had an understanding and I don't think I could do longer than the stints I was doing because of the implications."
Leuluai, who is remaining with the club as their welfare support officer, joined Leeds from Manly in 2006 and is their most successful overseas player of all time.
He says there are no fears for his long-term health.
"You can get it shocked back into a regular rhythm but I've had to wait as, after you've had it, you have to be out for three months because of the procedure and you have to go on medication," he added.
"It's quite common in cyclists they reckon, but it's strange for a rugby player to get it. I took the medication and thankfully it got me over the line."