Freddie Roach to Jesse Jackson: Here's How to Kick Parkinson's Ass

Legendary trainer Freddie Roach has a potentially lifesaving tip for Rev. Jesse Jackson in the wake of his Parkinson's diagnosis -- strap on the gloves and start boxing!!

Freddie's speaking from personal experience ... conquering Parkinson's for over 3 decades with the help of hand-eye coordination drills (AKA hitting and holding mitts).

"Boxing probably saved my life," Roach told TMZ Sports at his Wild Card Boxing gym in L.A.

Jackson says he's gonna do whatever it takes to fight the disease ... so Roach's sport could be a real option for the Rev.

But whether or not takes up boxing, Freddie's got a powerful message for RJJ -- "You just can’t give up, can’t let it take over."