Maybe it’ll be this week. Maybe next, or the week after. But before long, the weather’s going to make its shift to the consistently colder days of fall and winter. While that change certainly brings a lot to look forward to on the calendar, it can also bring extra challenges when it comes to keeping up with our physical activity. The result, not surprisingly, is that many of us are less active during the chillier months. “There is a seasonality to physical activity levels,” said Elizabeth Salerno, a behavioral scientist at Washington University School of Medicine in St. Louis who specializes in physical activity research. “So, if you feel your activity routine slipping as the weather turns, you’re not alone. And there are ways to maintain movement despite the cold.” Keeping up our routines, or maybe even building on them, is one of the best things we can do for our health and overall wellbeing. Activity, even modest amounts, helps lower the risk of conditions like heart disease,…