Sometimes it seems as if life is conspiring to prevent us from
exercising. We all know it’s good for us. And yet there’s never any
time.

Our parents and grandparents didn’t have any time, either. But they
never worried about going to the gym. And they were a lot less concerned
about gaining weight.

The difference is that we have steadily engineered physical activity out
of our daily lives. Since 1960, the proportion of trips to work by
walking has declined more than 70 percent. Once we get to work, we send
e-mail to coworkers instead of getting up and going to talk to them. We
use electric staplers. Few can remember the time when people cranked the
mimeograph machine.

The typical woman who spends 14 years in a sedentary job will gain an
extra 20 pounds compared with women in the least sedentary jobs,
according to a study published by the National Bureau of Economic
Research. And the Urban Institute reports that the number of workers
involved in physically demanding jobs has dropped from 20 percent in
1950 to 8 percent today.

Things have changed at home as well. We burn 20 percent fewer calories
on housework than a generation ago. Rake sales are down, while leaf
blower sales are up. Push lawnmowers gather dust in the garage, while we
drive mowers with engines more powerful than the ones in early
automobiles.

How about travel? I’m old enough to remember people actually lugging
their luggage rather than rolling it. And when did airports get moving
sidewalks?

It might not be technically true that grandpa got to school by walking
three miles in the snow, uphill both ways. But a generation ago, 80
percent of children walked or biked to school, at least occasionally.
Now, more than 80 percent never do.

Today’s kids are six times more likely to play a video game than ride a
bike in a given day. Meanwhile, just a quarter of high-schoolers are
enrolled in PE class at any one time. No wonder there are increasing
numbers of pudgy kids.

We are now seeing more and more policy proposals to address this falloff
in physical activity. There’s talk of subsidizing gym memberships and
redesigning communities to encourage walking. Some think that planners
and architects should submit “obesity impact statements” along with
their environmental impact statements.

But even proponents recognize that this is just nibbling around the
edges. The changes in our lifestyle are so profound that, short of
mandatory boot camp, no regulation will make any real difference.

Realizing this, some activists and academics concerned about obesity are
inclined to regulate food. They discuss extra taxes on snacks and candy,
zoning restrictions on where restaurants and convenience stores can
locate, mandatory portion size reductions, and minimum-purchase ages for
candy akin to those for cigarettes and alcohol.

Even if you aren’t worried about the implications for personal
responsibility, it’s easy to see that these proposals won’t take a real
bite out of our waistlines. You can eliminate super-sizing and subsidize
broccoli all day long, but if I can hit the all-you-can-eat buffet and
then buy chocolate syrup for less than a dollar a pound on the way home,
it won’t make a lick of difference.

Times have changed. You can go a month without ever breaking a sweat.
Buying tasty food is easy and inexpensive. Those in the growing ranks of
former smokers tend to gain weight (CDC researchers estimate that about
a quarter of our weight gain can be traced to smoking cessation).

Lest it be forgotten, these changes are, for the most part, good things.
Hunting and gathering may have kept us slender, but few would wish to go
back.

Short of a magical pill, foolishly encouraging everyone to take up
smoking, or abandoning the conveniences of modern life, top-down
solutions to obesity just aren’t going to work. We can’t legislate our
way out of this problem.

Weight gain can best be tackled person by person, family by family. Take
the stairs. Break out the push lawnmower. Choose diet soda. In short,
take responsibility. It’s not just a good way to go. It’s the only way.