Exercise dramatically slows the aging process, helping people look and feel decades younger, new research suggests. British scientists compared a group of 125 avid cyclists between 55 and 79 years old with a group of inactive older people and younger adults in their 20’s and 30’s. They found those who routinely biked long distances had more muscle mass, less body fat, and healthier cholesterol levels than their sedentary peers. The cyclists also had the memory, balance, and immune system function of the adults roughly half their age. As people grow older, their bodies make fewer and fewer T cells, which help protect against infection. Researchers found, however, that the active older adults were still making as many T cells as the people in their 20’s, potentially reducing their risk for infections, cancer, and auto-immune diseases, NBCNews.com reports. With people living longer, study author Janet Lord says, exercise can help keep you healthy and active into your 80’s. “We hope that this will really encourage adults to stay as physically active as they can,” she said.