3 weeks without smoking: what happens to your body

The NHS says circulation improves between 2 and 12 weeks after quitting, so blood flows better to your heart and muscles. Walking and climbing stairs often start to feel a little easier around now.

Your lungs are recovering too. The American Lung Association says lung function begins to improve between 2 weeks and 3 months. Cleveland Clinic says inflammation and mucus production calm down in the weeks after quitting, while the cilia keep regenerating over a few months.

On average, withdrawal symptoms last 3 to 4 weeks, though the NHS notes some people feel them for a few months. A research review found the core symptoms (anger, anxiety, low mood, poor concentration, impatience, insomnia and restlessness) last 2–4 weeks. Quit (Australia) says that for many people, withdrawal is gone after about two to four weeks.

So at 3 weeks you may have good days with almost no symptoms, followed by a day where a craving or a low mood hits out of nowhere. That pattern is normal. The NHS says mixed emotions in the first few days and weeks are common and will pass.

The NHS says that once you reach 28 days smoke-free you are 5 times more likely to stay quit for good, and suggests steering clear of triggers for those first 28 days. With a week to go, keep doing whatever got you here rather than easing off.

When a craving comes, the NHS suggests a quick burst of activity, reminding yourself that cravings pass, keeping your mouth busy with sugar-free gum or carrot sticks, and slow deep breaths. If you use nicotine replacement, keep following the course on the pack or from your pharmacist rather than stopping early.