First off, make sure that your file cabinet (or office wall) isn’t going anywhere. It should be stable and anchored. Then, just like at the gym, roll down into a seated position (ladies, take your heels off) and hold.
I usually hold at least 30 sec or closer to a minute if I can afford the time.
Today’s Move: File Cabinet Sits
Can you feel the burn? I can. Cubicle butt will be gone soon enough.