One reason I am keeping my coffee for now is because it warms my body. I can take Moose for walks early in the morning and not at all be affected by the cold temperatures because it's flowing in my blood. I go out two hours later to take the girls to school and am freezing. The walk goes by so quickly (and enjoyably) right after my coffee, but if I go in the afternoon, it seems to take forever, and my nose hairs freeze.
I think this is the way the Holy Spirit works in us. He wants to fill us so much that we are unaware of the nasty stuff going on around us; unaffected by the evil - overflowing with a sense of "peace that passes understanding" (Phil. 4:7), something beyond which we can fathom! That is an awesome gift, one that I need to remember that I have more often. And be aware of throughout the entire day.
Another thing it does is wakes me up! The Holy Spirit wants to do that for us, too. Living life to the full is something we can do when we realize that, as His children, the same power that raised Jesus from the dead is living in us!
I can only have coffee in the morning, otherwise I feel dehydrated. Something very different from the Holy Spirit; we can be filled with Him all day long, and it only gets better...