A quick and safe core exercise is the Halo. It can be performed on one knee, both knees, standing on one leg or both feet.
1… Choose a lighter kettlebell. Hold it upside down (bottoms up) in front of your face.
2… Turn the bell sideways by your ear, bring it behind your head, by your other ear, then back in front.
3… Go back the way you came.
4… Try and keep the whole body still and just move the arms. If there’s one spot in particular that throws you off balance, go slower through that spot and gain control.
Do this between sets or as part of your warm up. Keeping your body still really makes the halo challenging. Get a few each direction and then get back to work!