There's a thin line between being hard-working and being overworked, Syesha Mercado has found.

She crossed that line often in the early weeks of "American Idol," she told reporters today. "It was really hurting my performance. (Then) I became more comfortable."

Then again, overwork is understandable, considering her childhood struggles.

Mercado, 21, was ousted yesterday, leaving two Davids (Archuleta and Cook) for the Tuesday-Wednesday finale. In one film clip yesterday, her father mentioned his struggles with drugs and alcohol.

Yes, Mercado granted today, that probably shaped her personality.

"I told myself, 'I'm not going to be what my dad is showing me right now. I'm going to make him proud of me and some day, I'll be proud of him.' "

Like some others who grew up around alcoholism (including Bill Clinton), she compensated by being an overachiever.

"I've been a busybody," she said. "In school, I had to be in some play or something, all the time."

That habit has continued in college (Florida International University) and two reality shows. She was in "The One: Making a Music Star," which ABC canceled almost instantly in 2006, then soared on "Idol."

In some ways, her diligence has been helpful. "Idol" people praised her progress as she leaped between genres.

And in some ways, it was limiting.

"I'm goal-oriented," Mercado said. The hard work was often obvious in her performance; the fun wasn't.

During auditions, Mercado had mentioned her father's struggles. She didn't bring that up afterward, but reporters nudged her on the subject after his comments on the show.

He's doing well now, she said ... and her own ambitions are unrelenting. "I want to do everything ... And I will do everything I want to do."

She wants to do Broadway musicals — especially "Once on This Island" — and make a movie and start a restaurant and start a homeless foundation.

And she wants to do an album, something in the Christina Aguilera and Alicia Keys mold. She'll do it, one assumes, quite diligently.