Bike Chick, I know for me, it has to do with a lifetime of being the "last picked" for sports and growing up in a family that was afraid of anything that required the least little bit of risk. So, while my mom was athletic, given the constraints of when she was raised, it wasn't developed. I inherited her endurance capacity, though. My dad is totally uncoordinated and never did any sports. I have poor eye hand coordination and spatial skills, so the things that I do, are a real accomplishment for me. I have probably "over-achieved" given my deficits, but inside I still feel like a loser... there are a couple of things in cycling that are extremely hard for me (descending) and no matter how much DH coaches me, I freeze. I just get completely jealous and mad at myself for not pushing through. While I have much more discipline, i.e. I do a winter training program, I do some kind of exercise 6 days a week, and I do lots of different activities, DH generally does very little except cycling and x country skiing. And it took until this year for him to actually like the skiing. He stays active by doing a lot of outdoors work around the house and he is very strong. He gets on the bike in March, and is able to ramp up as quickly as me, with less training over the winter.
The best example I can give is that DH doesn't get why I can't remember what to do while descending. I say, I remember, I can parrot it back to him, but I can't do it. It's not natural, I feel like I am going to fall over. He finally understood how I feel when i tried to explain how to conjugate a verb in Spanish and how to use the different conjugations. He could parrot it back, but when it came to him actually using the information in a sentence, he couldn't.
So, while it was fine for me to coach him through the core work in our winter training a couple of years ago, I paid for a personal trainer a few years ago, when I wanted to work on the same things.