Can’t fit into your skinny jeans or cinching your belt at a new notch now that the holly-jolly season of overindulgence is over? If aesthetic reasons alone aren’t enough for you to shift your fitness program into full gear in 2012, then consider the health dangers associated with a sedentary lifestyle. Physical inactivity, according to the American College of Sport Medicine, can lead to cardiovascular disease, stroke, hypertension, diabetes, osteoporosis, obesity, colon cancer, breast cancer, anxiety and depression — real reasons for starting or resuming a fitness regime.