I think all the advice that needs to be given already has been, so I'll just answer your question. How do I keep doing it? I view the bicycle as transportion and not recreational equipment. It is the most efficient means of transportation that mankind has come up with yet. Until I started working from home two years ago, I always thought recreational riding was silly. I much prefer to have a destination than riding for the sake of riding, so commuting on the bike has always been a no-brainer for me.

My last regular commute was 23 miles each way. As far as 26 if I felt like taking the scenic route. I still have occassion to go to that office, but only about once every two weeks, so I've learned to embrace the joy of riding for the sake of the ride. As much as I enjoy riding 3-4 hours a day, others have brought up the point that long commutes start to be consuming and cut into family and social life. If you are comfortable leaving your car or bike overnight at your place of work, alternating one-way commutes are a good compromise to get used to the distance and ride time.