i ran cross country for 4 years and ive been running all my life. But i have never smoked but i can tell you this. You are going to hurt alot for the first few weeks/months. But after that, if you dont give up you will be back to the original shape. Its just going to take longer. Smoking kills your performance alot. But its nothing you cant recover from. Just go out and run as much as you can, dont matter if it hurts or what. The reason you could only run a mile is because you gave up, seing that you only ran for one year, i can tell you that you could have easily gone for 2 maybe 3 miles. Its just that your just not as mentally strong as you before. Go out and try 2 miles and i guarranty that you can do it.