When I am on tour I cycle about 100 - 130 km (80 miles) per day, every day, for 2 - 3 weeks.

Besides I cycle on tour with panniers, which contain the tent, sleeping bag, alumat, food, etc.

It does not wear me down, though I am not that young. I never feel myself better than on tour.

I know tourers who cycle 280 - 300 km per day. One of them cycled from Spain to North Cape in Norway for 10 days only.

If your work involves a lot of seating, than you will have time to rest.

After some time your avarage speed will increase and your commute will take less time.

If you can keep commuting 80 miles for a year, you will look so sporty, that you will have to marry again, as you will definitely become the center of the feminine attention.

We do not know much about your route. The majour problem could be head wind, darkness in the morning and evening, uphills.

I would advise to take on such a long ride the small medical kit. And I would also advise to check that the bottle with the hydrogen-peroxide is not dry. Sometimes a small wound may get infected and become the big problem (I learned it hard way).