You crack me up. Yeah, I think I was your age when I got 'moving'. And, yes, my mother also always made comments about her size compared to mine and how I must take after my fathers side.
But, the energy thing. It takes energy to make it. That is where I got started. I so much rather enjoyed sitting out in front of my friends house watching the traffic, chatting, enjoying her company. But we realized we'd sit for a couple of hours and get up TIRED. So, we started walking and talking. That was it. I don't think I'd have walked the 'hood alone, at first. Weird to walk around your neighborhood, ya know? We learned which houses had dogs, etc. I eventually was comfortable to walk alone, on the days she couldn't. From there I was getting energy and I gradually did more.
Good luck with it, even if you don't lose a lot of weight, the feeling of having energy will be great. Oh, and also, it helps relieve stress for me.