In reality It's a combo platter depending on my mood and the conditions. With that said I live a mile from the country's first "bike commuter highway" MUP, the Cedar Lake trail in Minneapolis and my office is 2 blocks off it on the other end.
There is no excuse for me and I live and work where I do by design to make bike commuting easy. It is an absolute breeze. So much so that I've done the entire thing (7.5 miles) no handed just to do it.