If you think this is easy, then I think you are missing something. This is hard. You need to know your hardware intimately to figure this one out.
Free Less Is More Hacker tee-shirt to the first correct answer in the comments. More details and demo video below…
Everyone loves blue LEDs and everyone loves coin cell batteries, but if you want to power a blue LED from a coin cell you will need some help. Here is a super-cheap and easy way add a to boost your LED voltage with only an additional capacitor & diode, and a little software.