Shawn Johnson Exclusive: 'I Had to Stand Up' to Stalker

June 22, 2010— -- Gymnast Shawn Johnson captured the hearts of millions with her athletics in the 2008 Beijing Olympics, but one man took his admiration for her much too far.

Earlier this month a judge found 36-year-old Robert O'Ryan guilty of stalking Johnson after police uncovered what appeared to be a potentially deadly plot to kidnap the sports star in March 2009.

Even though it terrified her, Johnson said she took the stand and faced her stalker because she said she "had to."

"I didn't want to. I kept asking if I could stay in the back room or go home," Johnson told "Good Morning America" in an exclusive interview. "I had to stand up for everybody else out there that's been through it... I just had to go there and kind of help put him away."

For much more on this story tune in to "Nightline" tonight at 11:35 p.m. EST.

Earlier this month Los Angeles Superior Court Judge Michael Pastor found O'Ryan guilty of felony stalking and burglary charges and two misdemeanor concealed weapons violations. The verdict came after four days of testimony and evidence.

O'Ryan was arrested on March 23, 2009, after driving from Florida and allegedly jumping over a fence at the television studio where Johnson was a contestant for "Dancing With the Stars."

Police searched O'Ryan's car and found two loaded guns, duct tape, a wooden club and handwritten poetry by O'Ryan to Johnson. In one passage, O'Ryan wrote, "No matter what happens I will always love you."

"Before all this happened, I thought I was invincible," Johnson told "GMA." "I thought nothing like this could happen to me and nothing would ever happen. But it was a reality check. It made me change the way I go about everyday life.... You hate to say, it's real."

O'Ryan had pleaded not guilty by reason of insanity. Despite the guilty verdict, O'Ryan was ordered to go through a mental evaluation.

He could get close to six years in state prison if he is found to be sane or, potentially, the rest of his life in a mental hospital if he is found insane.