dinosaur here: i had radiation for a recurrent brain tumor 40 yrs ago. so it was almost a different animal than what is used now---
!!! -the techs went into another building before starting the ray guns on my head !!!
i went for 6 weeks 5 days a week for about 35 min each time.
that said...my worst response was fatigue and weakness. BUT i didn't even realize that i was weak!! denial is a marvelous thing! LOLOLOLOL!!
i lived alone at the time, meaning i had no one to drive me to and from the hospital, 30 mi away. i had to take two buses and walk home 1/2 mi uphill for the second half of all that. it was probably what kept me healthy and strong! soon after, however, i was able to go cross country skiing and run in a half-marathon 🥰!!

this does not mean you won't have a more debilitating, emotionally laden experience but i wanted to share what it was like for me.