I have just started bike commuting again. I drive to the train station, take my bike on the train and then have a 4 mile commute on my bike once I get off the train. It's mostly downhill on the way into work, which is nice because I don't get too sweaty, but that means it's mostly uphill on the way home.
I'd love to bike the whole way, but it is 18 miles and 36 miles in a day would be too long for me at this point.
It's only 5.5 miles but it would be dark and there are no bike lanes on the route to the train station.
Maybe one day.