The 30-year-old returned to Headingley in late April but suffered a health scare within hours of training with his new team-mates for the first time.
Hardaker has now fully recovered from his seizure and is ready to line up for Leeds at the AJ Bell Stadium this weekend.
He believes his high-profile exit from Wigan Warriors and the swift move back to Yorkshire may have contributed to the fit.
"I've had all the tests and have been to a neurologist and to see about my heart and I'm really good," said Hardaker during today's press conference.
"I'm pretty fit, the doctor said. It's just one of those things you could probably put down to stress.
"I've had a lot going on the last three or four weeks regarding Wigan and coming home, and half my stuff being in Wigan and half at home.
"I was trying to get a team sorted and then training. I was a bit all over the shop and not 100 per cent healthy.
"I've had all the tests and they've come back really positive."
During his first spell with the Rhinos between 2011 and 2016, Hardaker won three Super League titles and the Man of Steel award.
Leeds are in ninth place after a slow start to the season but with 16 rounds still to go, Hardaker is confident Rohan Smith's side can secure a play-off spot.
"I really believe so," said Hardaker, who has scored 67 tries in 155 appearances as a Rhinos player.
"Wigan and Saints are the two teams going really well at the minute but everyone from third down is scrapping for those places.
"I've had a look at the points difference and where I feel the club could finish and there's no reason why we can't finish top six, one hundred per cent."
Hardaker's future beyond the end of the season is uncertain after he signed a short-term contract with Leeds.
His immediate focus is on proving himself on the field but he is open to an extended stay at Headingley, a place close to his heart.
"I'm not going to look too far ahead," said Hardaker.
"The deal is until the end of the year and I'm really happy with that. It gives Leeds the opportunity to see me and gives me the opportunity to see if I want to be here for the next few years.
"I've got to play well to earn a contract and Leeds benefit from that from me playing well.
"The club itself is massive and just coming back in it feels like a really good fit. It feels like I have come home a little bit."
After the struggle of being away from his young family while he lived on his own in Wigan, Hardaker is ready to show his best form now he is settled again.
"My family is really happy back home and I've been back a few weeks and am really, really happy," he added.
"Just to see my boy every morning and every night is all I've wanted for the last few months.
"I'm really happy with that and it helps me come to training with a smile on my face. Hopefully that can impact me on the pitch as well."