Sandbag Push Up
1) Get in the plank position - start on all fours and extend your legs back behind you. Put your arms directly under your shoulders.
2) Put the sandbag on your back (someone may have to assist you).
1) Slowly lower your chest to the ground - make sure your elbows are behind your shoulders.
2) Pause at the bottom, then 'push up' (think as if you're pushing the ground away) until you're back in the plank.