Aging baby boomers who neglect their health and fitness don't just harm themselves. Their lifestyles also affect their adult children, who eventually could end up caring for them - both financially and physically - as their health declines.
Of course, that's not the only reason those adult children might feel concerned. They also may like having mom and dad around and want that to continue for years to come.
So, they have a vested interest in encouraging their parents to get fit and stay fit.