🌲 Your immune system gets a powerful boost from forest bathing. Research shows that spending time in forests increases natural killer (NK) cell activity by up to 50% — these cells are your body's frontline defense against cancer and infections. This immune boost can last for seven days to a full month after your forest visit, making it one of nature's most effective health interventions. Trees release aromatic compounds called phytoncides that we breathe in, with levels increasing sixfold in our bloodstream after just one hour in the woods. These natural chemicals dramatically enhance our NK cells' ability to eliminate cancer cells. Studies comparing forest vs. city trips found that forest bathing increased NK activity by 80% while city walking only managed a 10% boost. Monthly forest visits may be enough to maintain elevated immune function permanently. Want to supercharge your immunity naturally? Aim for 2-4 hours in the forest for maximum benefits, though even 15 minutes can help reduce stress. The deeper into nature you go, the stronger the effect.