For some stupid reason I started smoking in Highschool. I then continued this till I was 27 and 100lbs overweight. In 2006 it was late July I had some car troubles and was working 100+ hours that week. It was a 3 hour break in a 16 hour shifts and the oil pump went out of my Jeep. I thought about it and decided I only live 3 miles from work or so I'll go to my parents and get my old mountain bike and ride to work. So I got a ride over there and air up the tires (5 years or more since I rode) and took off home. I took 8th street too work. I really had a great time doing 12 mph and not able to breathe. Upon arrival at work I sat down in the smokers room and lit up my prework smoke. 5 different people asked if I needed medical attention I was pale white and couldn't breathe. After 45 minutes I recovered enough to work the night. After the next 2 weeks of riding it was getting alot easier and I felt a bit better. I had decided to keep riding since my Wife had done the weight watchers thing and I was feeling the push there, I thought if I keep riding I can skip the diet. Some time around February I decided to trade off smoking for a new bike (trek road bike). I lost 85 pounds haven't smoked in 3 years and went from a new road bike to ride to work to 10 bikes, racing, joining a race team.
So I think even though cycling cost far far more than smoking (at the moment double) I do have some cool bike to show for it after 3 years and am in the best shape I've been in since freshman year in high school. All I had to show for the years of smoking was nothing. My original goal was to not gain anymore weight and be able to walk up 3 flights of stairs without resting at the top, and to save a couple hundred dollars a year in gas. I now have done a 200 mile ride (13.5 hours) Many 100 milers, 5 crit races, 2 mountain bike races, 1 cross race, A lot of rides, 2 running races, and many miles to go. My goals have changed a lot I'm starting mountain bike racing this year (jumped in head first) and still would like to hit 10k miles in a year.
If you think you can't then don't try, because success is for the positive. Stop talking about goals and just go win.