I smoked 40+ a day, too, for over 40 years, and I thought I wouldn't be ABLE to quit. I really didn't WANT to quit. But one day I tried this horrid little cigalike, and damned if it didn't keep me from smoking for the hours that it lasted before it died. That's when I knew it was possible, and ordered an EVOD starter kit. Now I use bigger mods, and bigger tanks, but the EVODs got me off the cigarettes, and I was able to just put them away the day after I got my starter kit. I think I smoked two after I got the kit, one the next morning, just "because," and one that evening, to see if I still liked it, and to my utter astonishment, I didn't finish that one. It wasn't bad, but it wasn't good, and all I could think of was finishing it so I could go back to my raspberry flavored vape. So I quit the smokes just like that and never had another one.
I wanted to have a cigarette many times (mostly when I was very stressed or anxious) in the first few months, but I'd put them away so they weren't handy, and I'd just grab my vape and puff on that. I chain vaped a LOT, but that kept my MIND thinking I was smoking and I figured it wouldn't hurt me, so why not? Now I vape about as much as I used to smoke, but maybe more, and that's because I'm hooked on all these wonderful flavors now! LOL! I've dropped my nic level down to one mg in the mornings, and zero nic in the evenings.
Haven't gained weight from quitting cigs, but it's winter up here in the far north, and I've put on my 10 pounds of extra winter insulation.

It'll go away in Spring, but it would be a LOT worse if not for these tasty e-liquids. I make my own now, and have been indulging in cheesecake and cupcakes and brownies and all sorts of decadent things, the best part being there are no calories! I predict that once I go back to my summer eating patterns, I might actually lose a bit of extra weight, because vaping keeps me from wanting to snack.
My health has improved greatly, not just being able to breathe better (I never realized just how bad it was until I quit smoking), and being able to smell and taste so much better, but I don't get as tired as I used to and I can do more physical labor without that horrible muscle burn when your muscles don't get enough oxygen. Now my muscles get all the oxygen they need. I also seem to have lost my "heart problem" that all my life I thought was a congenital birth defect thing. Now and then, especially if I was stressed out, my heart would do a short-circuit kind of a thing, which is too long and involved to try to explain, but it would beat twice as fast, and my blood pressure would drop down to around 60/40. It felt like I was running, no SPRINTING, up a steep hill. I couldn't stand or walk very long without danger of blacking out because no blood was getting to my brain. And sometimes those episodes would go on for hours... come to find out, apparently nicotine caused them. I never made that connection, because it's been happening to me since I was a kid, but then I realized, I've been a "smoker" since before I was born because both my parents and everyone they knew smoked. I had never lived in a smoke-free house until 6 months ago, and here I am, 58 years old now. So I guess you could say I smoked for 57-1/2 years! LOL! Anyway, since I've dropped my nic level down to near zero, they've completely stopped, but if I chain-vape even the 1mg nic juice for a while, I might feel a little stutter or flutter, and I know it's time to back off again.
I know that was too wordy, but I appreciated getting information like this when I was starting out, so hopefully some of what I said will help you.
~Lannie