You've got it! Start easy. Short rides then gradually increase in length and intensity. After not riding for 7 years I couldn't make it around the block (about 5 miles) without huffing and puffing. Now only a few months later I commute 17+ miles home from work and hardly even breathe hard (well I ride a 'bent and that helps). Last weekend I went out for a club ride, which included a 10 mile ride from home to the ride start and another 10 miles from the ride end back home. Total mileage for the day was 41. All on two bowls of ice cream (hey it was in "ice cream" ride) and a jug of sports drink.
Work on the smoking issue and getting yourself in shape through cycling. You will never regret it.
'bent Brian