Supreme Court Justice Ruth Bader Ginsburg may be an unlikely fitness model, lacking the muscle poundage of Dwayne Johnson or the rippling, always-exposed abs of Jillian Michaels. Nonetheless, the still-spry 84-year-old has attracted admiration in recent years for her unquestionably great stamina.

Wondering where she gets her strength? Apparently youre not alone. The Associated Press reports that Ginsburgs trainer of nearly two decades, Bryant Johnson, will walk America through her regimen in a book, The RBG Workout: How She Stays Strong... and You Can Too!

A few hints : Johnson has Ginsburg do push-ups using her feet, not her knees; she does planks instead of sit-ups; and medicine balls are involved.