Those who claim that the “individual responsibility” provision exceeds Congress’ power to regulate interstate commerce because it penalizes “inactivity” are simply wrong. Individuals who choose to go without health insurance are actively making an economic decision that affects all of us.
I hope it's clear to them what a dangerous precedent this would create. If doing nothing can be construed as an economic act that affects all of us, then what can't be? For example, once I've been forced to buy my health care, then literally doing nothing can be hazardous to my health. This potentially raises my future health care costs, and when those costs are shared by all, it affects everyone. Therefore, according to the White House's logic, it would be perfectly Constitutional to fine me for not exercising.
Of course, many liberals may well believe this. Nancy Pelosi expressed shocked disbelief at the notion that the PPACA's health insurance mandate might be unconstitutional. When Elena Kagan was asked during confirmation hearings whether a law requiring people to eat vegetables would be unconstitutional, she evaded the question.
Simply put, the left does not believe the Constitution is a "living document". They believe it is an irrelevant one. Only when the Constitution happens to coincide with one of their sacred cows do they recognize it; whenever it poses the slightest barrier, it is met with utter disdain.