Get down at a block before your destination and walk the rest
of the way. You might not have time to fit in long walks in your
busy schedule so this is one way of ensuring that you at least
get to walk for a little bit every day. If you take the bus or
the subway, get down at an earlier station and see if you can
walk the rest of the way.
If you drive to work, see if you can get space in a parking lot
that is a little away from your office.