I’m agree with how everyone has responded so far. In short, I see the equation as follows:
Absence of physical activity now = Consequences arising later
These “consequences” are often due to the cumulative effects of leading a sedentary lifestyle finally taking their toll. Michael’s link lists some of the major ones (i.e. obesity, back problems, etc.).
I especially like Joanne’s statement of, “We all know what happens when we don’t engage in physical activity.” Simple in form, yet it alludes to such a complex dilemma. Well said!