4. Upward Plank
In upward plank (purvottanasana), you face upward with your hands as your base and fingers facing forward. Lift hips and hold. This tones your lower back and opens the chest and shoulders. If you have shoulder or wrist pain, alleviate the strain by putting your feet flat on the floor with your knees bent and lift to upward facing plank from that position. The trick is to hold the position as long as you can to strengthen those abs.