The more you ride, the better your body will adapt, whether that's via the cardiovascular system or musculoskeletal system (although more than likely it will be both). I'd suggest riding more than just your commute though, especially if you like it. Keep at it and pretty soon you will find yourself accelerating up hills that used to kill you. The whole thing is circular: the better you get, the more fun you have, the more you hunt for challenges, which means you get better, which means more fun, etc.

Six months into commuting, I suddenly realized I was making better time to work on my bike than I was a year ago in my car.