Boat pose [0] is one of the best yoga poses you can do to strengthen your core, and here's a variation to make it even harder.

• Begin sitting on your mat. Lift your knees up to your chest, balancing with your shins parallel to the floor.
• Keep your spine long and your chest high, holding for one inhale and one exhale.

• Straighten your legs, and hold for one inhale and one exhale.
• This counts as one rep.
• Repeat for a total of 20 reps.