Anchor your feet under something and lean back until you feel your abs turn on. Try to keep your spine and neck as neutral as you can. You can go light and do the exercise for 60 seconds, or use heavier weights and shoot for 12-15 reps.
Maintaining the half sit-up position while performing any movement with the arms will challenge the abs, hip flexors, and even the neck muscles.
To win the war on der chest, we must attack it, Blitzkrieg style! We shall crush the pectoral enemy, see it driven before us, and listen to the lamentation of the vimmen!