You go, girl!
The Heathers star powered through her fatigue to bust her best moves alongside celebrity trainer Neda Soderqvist, while calling herself a "cancer slayer" and delivering a motivational message in the process!
The 45-year-old captioned the clip:
"Radiation is tiring. It builds up within you and sometimes one just struggles to keep their eyes open. You can see how tired I am here but I'm still moving!! Any movement is so good during treatment, not just for the body, but for your mind as well. #cancerslayer @jammalibu @themamarosa"
Be sure to check out her amazing moves (below)!