Below is a great video by "wreck ball method" on feet exercises. This is a relatively low impact method to train the feet muscles.
Animal flow routines are great for low impact workouts that will still get your heart rate up. It is great for grapplers and martial artists to build a strong core. Animal flow workouts are a great tool to combine with yoga workouts. They can be a great tool for warming up for heavy lifting seasons or can be used for active recovery tool as well.