Swiss ball stir the post is a great core exercise that will also work the lower back and glutes.

Begin by carefully setting yourself set up in a plank position your forearms on the swiss ball and your toes providing balance. Keep your stance shoulder width apart - the wider the base, the easier it is to balance! Once in this position, tilt your pelvis under, tucking your tail bone in and looking ahead towards your thumbs. Keep as flat a back as possible and engage your core muscles.

Once you are in a strong and stable plank position on the ball, start to move your elbows in a small circular motion whilst keeping a tall and neutral alignment. Start off with small circles and focus on keeping your body as still as possible. The more confident and experienced you get, you can increase the size of those circles!