Would you risk your life to save another person or have surgery to restore your sight, even though there are potential serious side effects? A two hour ''20/20'' explore amazing stories about making the most difficult and life-altering decisions. First hour: 1) When is it time to let a child pursue his/her dreams? Country singer Billy Ray Cyrus never wanted any of his five children to go into show business. He knew all too well how disappointing and difficult show business could be. He was so clear about this choice that he raised his kids in Tennessee in what most would consider the very ''normal'' circumstances. But one day his daughter, Miley, came to him and said she really wanted to pursue an acting/singing career. He tried to talk her out of it, but eventually gave in. Hannah Montana was born. In their first extended broadcast interview together, Miley Cyrus and her dad speak candidly about life in the spotlight and what they're doing to resist the ugliness that comes to some young stars. Deborah Roberts reports. 2) Not accepting a diagnosis: Instead of just accepting her son's diagnosis of autism as an incurable illness, actress and author Jenny McCarthy decided to take matters into her own hands. Deborah Roberts reports. 3) Whom do you tell when you've been raped? Kimberly Scott has had to face a series of tough calls throughout her life. As a young married woman, Kimberly says, she was raped by an acquaintance and then had to decide whether to tell her husband, Eric, what had happened. This difficult situation was made more traumatic when Kimberly learned she was pregnant. She now faced whether or not to have the baby and if so, whether to keep it. JuJu Chang reports. 4) My Sexuality or My Religion: Conversion Therapy. Is it possible to attend a kind of conversion, or ''reparative'' therapy to ''pray away the gay''? JuJu Chang reports on conferences, group homes and other therapy sessions aimed at men struggling with their same sex-attraction. Do these programs work or do they cause damage? Second hour: 1) When is it time to walk away? Chrissy Coppy and then 22-year-old Keith Cavill had been high school sweethearts and were talking about marriage when their lives were turned upside down by an unforeseen event. In August of 2003, Keith had a motorbike racing accident which left him paralyzed. Chrissy was devastated but hung on to the relationship, even as her role turned from lover to primary caretaker. Keith couldn't imagine life without her. But Chrissy was overwhelmed and she knew she had to leave. She made a tough call and told Keith she had to walk away. Elizabeth Vargas reports. 2) Would you risk your life to save another? Private Channing Moss was on patrol in Afghanistan with members of his platoon from the 10th Mountain Division from Ft. Drum, NY when he was struck by an RPG that lodged in his lower abdomen -- but didn't explode! The soldiers' rulebook dictates, in this rare incident, that the wounded soldier should be moved aside and made as comfortable as possible, but that the lives of others should not be risked to save his life. A series of tough calls, all against the rules, then ensued. Elizabeth Vargas reports. 3) Stay in a not perfect marriage or leave for another man? Pattie Boyd was a mate and muse to rock and roll royalty. Married to The Beatles' George Harrison, she inspired such hits as ''Something'' and ''While My Guitar Gently Weeps.'' She also inspired Eric Clapton's blockbuster songs ''Layla'' and ''Wonderful Tonight.'' Could Boyd choose between the two rock stars? Should she leave her husband for another man? Chris Connelly reports.