"My long term confidence in terms of my back, I am not even thinking about it right now," Day told reporters at TPC Sawgrass on Tuesday.
"I feel really cautiously optimistic about how things are progressing and the way that I feel."
Day said last week that an MRI scan had revealed he had a tear in a disc in his lower back, which was causing him crippling pain when the problem flaired up.
"When pain starts shooting down my legs, that's obviously a no-go," he said.
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"My back seizes up, and I can't really walk ... it feels like your world is ending. It feels like is this going to be the last time that I am going to pick up a golf club.
"It's not great mentally to come back from an injury so your confidence is hit a little bit, but overall I feel good about."
Day, who able to play 18 holes on Monday, said he had also spoken to Tiger Woods about having injections for back problems.
"My big concern was if I got them, how long would it last?" Day said.
"I have to be more disciplined with my physio and training ... We are all playing with some kind of aches and pains."
After withdrawing from the tournament at Bay Hill last week, Day decided to spend time with his family at Disney World.
That did not sit well with some on social media who wondered how he was unable to play, but was able to walk around a theme park.
"It was great," Day said. "When I have an injury, I get sad and depressed.
"I mean that's the biggest thing. I'm not going to be sitting in my bus depressed, and especially when the doctors tell me to go and walk."
Day said he was not going to let criticism on social media bother him either.
"I don't care, like, if people make memes about me. I think a lot of them are funny," Day said.
"I mean, it's fine. It is what it is. People trying to be funny and that, I get a good laugh out of it and I'm okay with that.
"You can tell between people that are being funny and people that are actually trying to ... that really hate you."
(Reporting by Gene Cherry in Raleigh, North Carolina, editing Nick Mulvenney)
