In sanskrit Paripurna means full or complete Nava means boat. Just like a boat in this pose you must teeter your weight forward and back in your seat in order to find the balance of engaging your core. Just like in most poses and life we want to find the balance of effort and surrender here. Making sure that the work you feel in your lower belly isn't tightening or work to hard into your hip flexors and at the same time also making sure that you round back enough to engage your abs but not so far you strain the lower back or have trouble keeping the spine lifted
Sit with legs out in front of you. Draw your knees into your chest with your hands holding behind your knees, lean back so that your feet start to lift off the ground. Keep working to straighten your legs but if your spine starts to round stop there and breath. Eventually you can work to straighten the legs and let go form behind the knees reaching the arms forward. Try to hold for at least 5 breaths and repeat 5 times.
Benefits of Full Boat Pose:
Tones and strengthens your abdominal muscles
Improves balance and digestion
Stretches your hamstrings
Strengthens your spine and hip flexors
Stimulates the kidneys, thyroid and prostate glands, and intestines