Return to Smoking and Tobacco 6 months 8 hours 48 hours 72 Hours 2 weeks to 3 months 6 months 1 year 10 years 15 years More good reasons The positive effects on the body after being smoke free for 6 months1: Your coughing, stuffy nose, tiredness and shortness of breath improve. 1. Health Canada, Tobacco Control Program. On the Road to Quitting - Guide to Becoming a Non-Smoker.