Why was I so upset?

When I look back at my last day of smoking, I can't believe how upset I was.  I was smoking one cigarette after another in just disbelief that I was quitting.  Now that it is day 8, I am not upset.  Sure it hasn't been the easiest thing to do, and certainly I have a long way to go.  But as I read further and further in this book, I am realizing that I wasn't really upset, but I was just scared.  Of what???? I don't know.  I should be celebrating.  I mean I have been free of smoking for 8 full days.  If I keep this up, I should be feeling many benefits that I haven't felt for a long time.  I should have more energy, breath better, save money, not waste time.....oh that's a big one for me, the wasting of time that cigarettes took from me and my family.  I know that I shouldn't overly expect too much, because there isn't too much more to expect.  But why......I mean why was I so upset???  And I somehow keep forgetting that I am an adult.....if I wanted to, I could just walk down the block and buy a pack of cigarettes and smoke them...I could.  I could also buy myself a six pack and drink it if I so choose.  I am not some teenager waiting to steal a cigarette from my dad, or waiting for my parents to leave the house so that I can break into the liquor cabinet.   
I can't look at my quitting smoking and drinking as a forever choice, but take it day by day. I also cannot think of it as being forced upon me because its not being forced.  I made these choices and that's the key....I MADE THESE CHOICES. However, if I found out the world was going to end tomorrow, you bet your ass I'd be smoking and drinking like crazy.  But still that would be my choice.