Set a timer for 2 minutes and hang your head off a comfy bench while laying down.

Simply keep your head neutral while slowly looking left and right, slow and steady movement.

If you can manage 2 mins, do 2.5 mins next time.

If you can barely do 2.5 mins then just keep doing 2.5 mins until next week where you try 3.

Do this every day. It gets tons of blood into the neck and you don’t need resistance. Your head is heavy enough.