Live in a metro area where there are laws that sidewalks have to be clear. I live in Boston and have been walking to work for the last 15 years including during the winter. The only exception is that I take the metro (or 'T' as it's called here) when it rains. It's very rare to have an impassible sidewalk, and when you do you just walk around it in the street for a few meters.
There are plenty of tech companies here within walking distance, lots of job options and an OK startup scene.
Also, don't have a car. I use Zipcar or taxis when necessary (maybe 10 times a year). Not having to pay for a car, insurance and parking saves a lot of money. That savings makes living in more expensive city apartments more easy to afford.
Not having to drive to work is my number one job perk, and living in a city is much more enjoyable (to me at least) than not.
Get a pair of Kahtoola microspikes and you won't have to worry much about falling on ice or snow. I run all winter in Montana with these. They handle streets or mountain trails without a problem.
