Sit-ups all day ..

GORUCK Heavy, Tough, and Light Training:

Within 1 hour of waking up, do a 2 max-situp test. Then, for the rest of the day, every-hour-on-the-hour, perform 30% of your max effort total.

Training Notes:

Yes, every hour. Really. Find a place and make it happen. If you want to do less, go to bed early.