Return to Smoking & Vaping 2 Weeks to 3 Months After Quitting 8 Hours After Quitting 48 Hours After Quitting 72 Hours After Quitting 2 Weeks to 3 Months After Quitting 6 Months After Quitting 1 Year After Quitting 10 Years After Quitting 15 Years After Quitting More Good Reasons Some positive effects you may feel during the first 2 weeks, to 3 months, of quitting smoking are: Your blood circulation improves. Your lung functioning increases up to 30 per cent.