I got a 19 mi o/w commute and usually start in the Spring, working my way up to more or less full time bike commuting.
Bring your bike in your car the first day, ride home. Ride back to work the next day. That would be a decent start. Or just commit to doing it once the first week, twice the second week, etc. until you're riding as much as you want to be.
But really, just do it. Thinking about it makes it seem a lot more improbable than when you are actually riding.