I don't know what everyone else is talking about but I breezed through rads/chemo. Where I took time off from the hotels I ran during the day, I managed to keep my second job...hunting ninjas sent by the government to assasinate me in the night!
Funny but true.
I suffered pretty bad side effects from Ambien and Lunesta, the sleep aides prescribed to counter the opiate induced insomnia. I don't remember much of that time due to the sheer amount of drugs I was playing with (liquid oxycodone is effective and the type I had tasted like cherries!) but I know I had an easy go of it!
I did go back to the hotel a week after rads and my last chemo, I lasted two days before physically before I had to stop again.
Just take it one step at a time and listen to your body, it will start talking pretty loud at you at some point and let you know when's a good time to take a time out.

Good luck, we all did it so can you!
Eric