The first meeting between the two in June saw Ruiz produce one of the greatest boxing upsets of all time when he defeated the previously unbeaten Joshua in New York to take the IBF, WBA and WBO belts.
Joshua will get a shot at redemption this weekend and the 30-year-old Briton revealed he has been advised by former world heavyweight champion Wladimir Klitschko.
The Ukrainian, who Joshua beat in a classic Wembley bout two years ago, suffered his own shock loss to Corrie Sanders earlier in his career but bounced back to become a world champion again.
"For someone who is going through success now, who is winning, definitely check yourself," Joshua told BBC Sport about the advice he has received.
"I have had to check myself and reinvent myself not physically, mentally."
Joshua, whose record is at 22-1, suffered an off night at Madison Square Garden having been sent to the canvas four times.
"There is fire in the belly," Joshua added.
"There are things I had had to do to take me to the next level.
"I am confident I can be victorious and when I am I will tell everyone of how I went wrong."