Physiologically, smoking does give you a higher hematocrit, but lots of good that does with small black lungs. I am a recovering smoker, and I can tell you for sure that I was way faster on the bike before I started to smoke. For me quitting had an effect on every single part of my life. It is a big deal. I would advise giving up a few other "triggering habits" for the first couple weeks-coffee and alcohol mostly. Start drinking tea in the mornings. I truly hope you can succeed. Check out whyquit.com if you need some inspiration/data. As a parting thought, my pops became addicted to heroin while in vietnam, he says quitting cigs was harder than quitting the smack- but it is possible, and you CAN do it.