First I just want to say that you shouldn't micro-wave your lemonade (I don't know if that's what you've been doing but I'm saying that just in case) because I THINK, it kills the vitamins in it.
Now about being cold, I also live in a cold climate (Montreal) and I found that there's not much I can do about that really... except wearing good clothes (maybe put on an extra pair of socks, wear 2 t-shirts under a sweater, etc).