Stretches
We highly recommend Yoga with Adriene on YouTube; not only does she have a cute dog who joins in on occasion, but she has many videos specifically designed for people with PTSD and anxiety/trauma. Move your body in a safe and comfortable way with one of her videos.
Task length: 10-20mins
ALTERNATIVE: If yoga and stretches are too triggering for you, consider doing some upper/lower body stretches that you find safe. Head and shoulder rolls, hip rotations, and prayer stretch are all great.