The Cardiff Blues captain received the welcome diagnosis in February and slowly worked his way back into the team.
But with a full pre-season now behind him, Rees is determined to enjoy the forthcoming season under new coach Mark Hammett.
"It was tough for me to come through the diagnosis I had, but I have come through it and I look at that now as the past," said Rees, capped 60 times by Wales and on three occasions by the British & Irish Lions.
"I have taken the positives out of it and I was just glad to get back playing towards the end of the season and getting some game time.
"It's a new season, it's a new start, we have got Mark in as the new coach and I think everyone is on a high at the moment and really looking forward to the season.
"We are definitely in a better place in terms of the strength of the squad than we were last season and that can only be good for players and good for coaches as well."
The eye-catching addition to the Blues squad this summer has been Wales' front-row Adam Jones.
Upon his arrival, however, Hammett ordered Jones to "shed a few kilos" in order to improve his mobility.
And Rees has backed the 33-year-old to succeed with his own personal challenge.
"Adam has been the in-form tighthead in Wales for a number of years and he has got a challenge on his hands," added Rees.
"He is one of the most professional guys you will come across and I am sure he will rise to that challenge. For us, as front rows, our challenge is making sure we perform the best that we can and only time will tell."
Cardiff kick-off their GUINNESS PRO12 season next Sunday at Zebre, before Glasgow Warriors are the first visitors to BT Sport Cardiff Arms Park.
And Rees has revealed his team-mates are in peak condition and raring to go.
"It's business as usual. From where we were last season compared to now I think we are a lot fitter," he added.
"I think the boys have had a tough pre-season, we're in pretty good shape and it's early days yet.
"But we have recruited well this season and it's about doing the talking on the field now."
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