I have an 84 y.o. aunt who started a serious exercise program about 4 years ago, working with a personal trainer. She's had good results. Nothing crazy, but good results. Her trainer had an interesting approach: strength training first, then cardio. Like a couple years of 3X/week strength training before even trying cardio. She's very gradually getting stronger and becoming able to walk 1 mile distances. Before the training, she was a typical sedentary - never did anything physical in her life, could hardly walk, used a cane, etc. So it's never too late, but the older you start, the smaller the expectations should be. My aunt is very pleased with her achievements.

For whatever reason, though I'm relatively unathletic, I've enjoyed engaging in athletic activity all my life, to the point that now I'm something of an anomaly in my peer group. I have no talent other than desire. It's like a lot of other things, heh. That last is the difficult bit. All the rest is easy. Or as randos say, "It's all between your ears."

I know 3 things: You cannot have a thought you cannot put into words. Your mental map must be congruent with the world around you. And never give up: when it gets tough, find another way to move forward.