Here's a nice exercise that can be done on any flat surface that is slightly above the ground. Use a plank of wood, a step or as in the video a weight plate. Take small steps around/along the surface with just the balls of your feet and toes touching the step. Aim to keep your heels parallel to the floor below i.e. not raising them up or letting them drop down.
This can help improve balance, foot and ankle strength. You may find it easier to perform this barefoot as you will be able to feel the step better without your squidgy exercise trainers on. Enjoy new levels of strength.