Pals of Lindsay Lohan tell People Magazine that the actress is thriving during her in rehab.

“She’s been sending text messages from rehab saying she’s the happiest she has ever been,” a pal tells PEOPLE in its new issue. “She seems under control right now.”

LiLo skipped the Sundance Film Festival to attend treatment meetings and go hiking on three acres of land at the Wonderland Center for addiction-treatment where she has been staying for the last week.

Wonderland features a spa, yoga instructors and beauty constultants. Dr. Howard C. Samuels is the center’s executive director: “We treat the individual’s emotional, spiritual and physical ailments.”

Production on Lindsay’s upcoming thriller, I Know Who Killed Me , is on hold while the actress completes treatment.