Brett Favre is taking an optimistic approach to his fight with Parkinson's ... telling TMZ Sports he "can't complain" about his lot in life -- although he did admit he is sometimes struggling, because "when I wake up in the morning, I feel like a board."
The Hall of Famer opened up about his disease on Thursday afternoon ... and check out his interview with us, it's clear, he's remaining super positive despite the dire diagnosis.
The 55-year-old says doctors have caught everything extremely early -- "In fact," he told us, "my doctor said you may be the earliest patient I've ever seen to come in."
He added that his medication has made all of his symptoms manageable ... and he's staying encouraged about the possibility of some sort of impending cure.
But, the ex-Green Bay Packers superstar did say there is one thing about the ordeal that's bothering him -- some tight muscles in the AM.
"With my Parkinson's, the main side effect is rigidity and stiffness," he said. "I have a little bit of shaking, but not much. But, rigidity and stiffness."
"When I wake up in the morning, I feel like a board," he continued. "I don't need any help because of football to be any stiffer. But, all things considered, I'm a very blessed man."
Favre was first told he had Parkinson's back in January -- following issues with his right arm and hand. In September, he revealed the diagnosis to the public at a hearing on Capitol Hill.
Since then, Favre told us he's been feeling a ton of love from friends, family and other supporters -- and even trying out various treatments to deal with the matter.