In-and-outs raise your legs and lower them ... I like to position a weight like one of the best kettlebells in front of me, or dumbbells to give me something to lift my legs over.
You can also try doing one-leg calf raises to help balance or using weights ... Stand on the edge of a step or raised surface with the front half of your feet on the step and your heel hanging ...
On your first try, make sure the leg that's in front is the side you're more flexible on, Sobers recommends. Your hands should touch the floor on either side of you. If you can't quite reach ...