She told the 65-year-old comedian that May 2 is her deadline to report for the three months of rehab that a California judge gave her for reckless driving and lying to police about a car wreck last June.
When Letterman asked how will this time be different from rehab stints, the 26-year-old said, "I think, to be honest, I'm the happiest when I;m working and the healthiest, and I think this an opportunity for me to, you know, focus on what I love in life. And I don't think it's a bad thing. I think it's a blessing ... and not a curse," she said.
Later Lohan wrote on Twitter that she had a wonderful time at the Late Show.