The thing about hormones is that they DO cause changes in ALL of the body. You are correct to say that the actual bone structure of the hands (or your body) does not change, since that is set after we go through the teen stage, unfortunately. We seem to not have developed the technology to mold the bones just like we mold the skin. I mean, I don't see why it isn't possible. But who knows? We may get there one day. That is off-topic, though. Anyways... While the bones do not change, I've heard that the appearance of the hands and feet DO change to a certain extent. I think it has something to do with the changes in the skin and maybe in the muscles. So yeah, I'd just wait and see.
As to your second question... It IS a good idea to do about 30 minutes a day of cardio in general principle. Walking or biking is very good exercise because it is low-impact, versus running, which is high-impact. I guess studies have shown that high-impact exercise does more damage than good? But another interesting thing is that a study showed that you have to bike four times the distance you walked to get the same health impact. So to get the benefit of a mile walk, you'd have to bike four miles. Now want to know what the best form of exercise is? Dancing! The reason is is that dancing uses every part of the body. This means that you have an excuse to do flash dancing or random dancing, lol. So I'd consider taking a dance class if there are any local ones. But if there aren't any, there are good dancing workouts or even dancing games. One of the more popular ones is Zumba, yet if you want something more racy, there is Flirty Girl. I've got both, yet I've yet to actually try it. Heh. Now there are video games like Dance Dance Revolution, Just Dance or Zumba. All would work. Oh, and once you start developing, I'd suggest getting a good sports bra or something. A little extra support never hurts, lol. The key? Just have fun and stay healthy. Drink water, too, and use proper breathing.
I'm glad that you are taking your health into consideration, though. It is always an important thing to do. And you are reminding me that I have to stop being lazy and start exercising, too. *raises a squeeze bottle of water* Here is to staying healthy!
