Country singer Jo Dee Messina is preparing to slip on her running shoes and compete in a marathon in Texas later this year.

The 41-year-old star, who gave birth to her second son, Jonah, in January (12), is planning to tone up her body by taking part in the Rock 'n' Roll San Antonio Marathon, but she will be under more pressure than most to reach the finish line - she's due to headline the post-race concert shortly after the run.

In a statement about the event, Messina jokes, "I'm not really fast, so I hope I make it back in time for the show. I hear they have a great one planned. I'm definitely more nervous about the run than the show. But, I'm looking forward to both."

Taking to her Twitter blog on Tuesday, she adds, "Got to start training for San Antonio marathon. It's nov 11. Whose Runnin with me (sic)?"