Although sometimes I just have to give in and crawl into bed at 7:00 pm, I try to strike a balance between activity and inactivity during the day. I sit all day for my job and I have found that much sitting can exacerbate my fatigue, so I try to make a conscious effort to just get up and move around every 15-30 minutes when work allows. Thankfully, the people that I work with know that I'm having treatment and are quite sensitive. If I am just too fatigued to deal with a problem, I can comfortably suggest to them that I deal with it the following day. I hope your people are as understanding.
I can't underemphasize diet. I have a recipe for a smoothie that I got from Prevention magazine. It contains a bunch of "super foods" and it helps keep my energy levels up. Avoiding processed sugars and simple carbs also helps (although during the holidays I am especially not good at this one).
Fatigue is really a pain in the arse and sometimes you just have to roll with it.
Best of luck with this.