Lie on side.
Put top foot in front of bottom foot (easier) or stack top foot over bottom foot (harder).
Push up into a side plank (use top hand if needed as a brace).
Use hand as a brace (easiest). Move hand to hips (harder). Raise hand in air (hardest).
Hold for 30 seconds to 3 minutes per side, breaking up with rest as needed.
» More on functional strength