Senior citizens can exercise for free on National Senior Health & Fitness Day. The National Senior Health & Fitness Day will be celebrated on May 29 at the MedCentral Health & Fitness Center, 1750 W. Fourth St., Ontario. The event includes free workouts to seniors all day, complimentary classes, screenings, refreshments and prizes from 8 a.m. to noon. A potluck will follow from noon to 1 p.m.  Research suggests that older adults live longer (and better) if they continue to stay active o...