Physical trainer when younger,worked out my whole life.strength,cardio,cross train,run,cycle.now a little older& beat up,just light cardio & stretching 4x week.i feel good.according to apple watch, resting hr 48 bpm. is this ok?

48/min can be normal if, upon arising and walking, the HR increases appropriately and if it continues to increase with a brief jog. With aging, an inappropriate slowing of the heart rate can occur, sometimes with intermittent rapid beating; that is called a bradycardia/tachycardia syndrome and merits a visit to a cardiologist.

The details you provide suggest that your heart rate ay be due to training effect rather than an abnormality with the heart. But it is always best to get a check-up including an ECG and possibly a Holter monitor. Have you had a physician look at the Apple watch output tracing to be sure that there is no rhythm abnormality other than sinus bradycardia and that medication do not have a role.