If you spend too much of your day sitting down, you are likely to have a shorter life span than if you sit less. Thorough research from a long-term (12 year) study of 17,013 Canadians showed that mortality rates increase with higher level of daily sitting time, independent of leisure time physical activity. In other words, the bad effect you get from sitting down for most of the day is not eliminated by increased exercise in your spare time. So get up from that chair!
Read the original research paper from Katzmarzyk et al.
Illustration courtesy: AdjustableBeds.com