I had 15 rounds of radiation I only felt tired for a few weeks after. Walking and staying hydrated really helped with it.

I've had radiation 5 times now. I've had rounds of radiation that lasted anywhere from 1 week and 5 sessions to 4 weeks and 20 sessions. I've found it typically takes me 3 - 4 months to recover from radiation and the side effects of nausea, lack of appetite, lack of energy, sore throat (when throat was radiated for breast cancer recurrence), and being super tired and needing to take naps on an almost daily basis, sometimes even 2 naps a day. I'm 6 months post radiation now from my 5th time around and I'm about as recovered as I'm going to be at this point. It all depends on how many sessions you have, what body part(s) get radiation, how big a dose of radiation you receive with each session, if you receive a radiation boost at the end of your radiation cycle, what type of radiation machine is used, and how long a time frame it takes to complete your radiation. For me if radiation lasts a week it takes me about 3 months. When radiation has lasted 3 - 4 weeks it has taken me about 4 months. My last round of radiation was 4 weeks with 20 sessions with a 4 day radiation boost at the end. My chest, armpit, and neck received radiation on my right side. Some people have an easier time dealing with radiation than others. Sometimes you will have side effects that last after radiation is completed and your body has recovered as much as it is going to recover. Some people get what is call "late effects" which is when some sort of side effect shows up weeks, months, or even years after you've completed radiation. My last round of radiation left me with emphysema in my right lung and damage to my vocal cords which has changed the sound of my voice. The skin on my chest where I received the 4 day boost at the end feels thicker than the rest of my skin even though I've been putting lotion on the radiated areas on a daily basis. On the plus side, at least for me, radiation has been much easier to deal with than having chemo. Good luck to you, I hope all goes well with your radiation ❤️