Everyone's ideas are good (use panniers, take rest days, etc.).

This may not work where you live, but if you have a car could you drive say 5 miles w/ your bike, park and ride the rest of the way (reversing the process in the evening)? You could build up from there, reducing the driving portion until you are able to bike the whole way.

Again, this is really dependent on (a) having a car and (b) having safe places to park all day long.