"First of all, wake up. Wake up and try to get your bones moving," a grinning Jones, who turns 82 this month, said ahead of the cast's first rehearsal.
"And then be enthusiastic about what you do. I'm very enthusiastic about acting still. I love the process of creating a character."
For 87-year-old Lansbury, whose seven-decade career has spanned stage, film and television, performing live gives her a rush that can't be matched on the screen.
"You get on stage and you really can let it out," she said.
Lansbury, nominated for three Oscars, played amateur detective Jessica Fletcher on the long-running TV series Murder, She Wrote.