Exercise is good for your health at every age—and you can reap the benefits no matter how late in life you start. That said, our latest research has shown that in the United States, people who were more physically active as teenagers and throughout adulthood had lower health care costs. For our study, we drew on data from the National Cancer Institute’s study on diet and health, which looked at more than half a million adults. As part of this study, adults in 1996 who were aged 50 to 71 were asked how physically active they were during this time in their life. They were also asked to estimate how much exercise they got in late adolescence and early and middle adulthood. We followed up with participants between 2004 and 2006. During this time, some consented for their study responses to be linked with their Medicare data. Medicare is the major health insurance program …