This is a great Men's Health abs workout called the "front-pillar with diagonal arm-lift". The bridge position is a fantastic core muscles workout for the abs.
Assume a modified press-up position with your forearms resting on the floor. Your elbows should be under your shoulders and bent to 90°. Keeping your torso steady, raise your left arm forward and to the left so that it points to 10 o'clock.
Hold it for one to two seconds then lower your arm. Next, try raising your right arm up to the two o' clock position. If you struggle to balance we recommend you spread your feet further apart to help give you a stronger base.
Too easy? Try lifting a leg at the same time to really work the core. For example, as you raise your right arm, also try to raise your left leg slightly off the floor while still maintaining a perfectly straight body. Breathe in at the starting position and breathe out as you lift your limbs.