Just turned 50. Female. Should I start exercising more?

Absolutely. Make sure you're healthy enough to do so if you haven't been exercising regularly already. Mother nature behaves like she meant for us to die after 45 as our eggs run out and metabolism slows. As cave people, we'd get fat, slow and be eaten.Look at persisting at regular exercise as a way of laughing in her face. Got to reduce calories, too, dammit. But the alternative is ... Well, worse!