After setting the bar so high with “Terminator 2,” could she be the character’s ripped, jacked self again at age 60-plus for “Terminator: Dark Fate”? After a year of working out with elite trainer Mackie Shilstone, the results were clear: Hamilton dropped 15% of her body mass — “a number less than most healthy, athletic 20 year olds,” he says — with increases in lean muscle, stamina and endurance.