The 'America's Got Talent' host was hospitalised over the festive season with mild kidney failure and he feels "indebted" to his spouse of three years for the way she looked after him and supported him during his recovery.
He said: "I'm happier than happy. Especially though this entire process, we've become so much closer ... I even got a chance to see a different side of my wife where she became so nurturing. I'm in debt to her forever. "
Nick was taken ill during a festive break in Aspen with Mariah and their eight-month-old twins Moroccan and Monroe, and doctors originally thought he had contracted acute mountain sickness before realising the seriousness of his condition.
He explained to radio host Howard Stern: "They thought it was kidney stones, then a kidney infection.
"They found out my kidneys were not functioning well. So we said 'mild kidney failure.' "
The 31-year-old star is now "feeling 100 per cent" but says his illness has taught him not to push himself so much.
He said: "Because of this situation I know that I don't need to go so hard. It's more about just my way of living ... It's really about taking some time."