A longevity expert says you should be doing this type of exercise by your mid-40s to slow the aging process Fit and WellOpinion | No One Tells You What Happens to Your Muscles in Your 40s The New York TimesHow to slow down ageing process at 40! Here's what you should do The Times of IndiaExpert explains why ageing process dramatically spikes at two exact ages and how to stop it LADbible