05/14/2012 AT 02:55 PM EDT
05/14/2012 AT 09:00 AM EDT
Sarah Hyland is young, beautiful
and on a hit TV show – but the Modern Family
actress has been quietly battling a serious illness.
Hyland, 21, has had a lifelong battle with kidney dysplasia and underwent a kidney transplant on April 13, 2012, she reveals in the new issue of Seventeen
, on newsstands May 22.
The actress, who got the kidney from her father and gave the interview while recovering from surgery, says the whole experience taught her who she can really
lean on in times of need.
"You know that family is always going to be there for you – no matter what. My dad gave me a freakin’ kidney!" she tells the magazine. "But it's also the families that you create outside of your family. And you really find out what kind of people you're friends with."
Continues the actress: "It was just amazing, and it really opened my eyes to see who's there for me and who's not."
One person who proved he's there for her is Hyland's boyfriend, actor Matt Prokop.
"He helps me with my medication and takes me to doctor appointments and all the stuff that I need to do to take care of myself," Hyland says. "Any other 21-year-old guy would not be there, I guarantee it. I am one of the luckiest people in the world to have him be there for me."
As for what she's thankful for, Hyland says, "I have a second chance at life – not a lot of people get that."