For the month of October do sit ups every day. Do 5 sit ups per the date for that day. For example: on Oct 1st, do 5 sit ups, on Oct 2nd, do 10 sit ups, etc.
Do real sit ups, not crunches or leg levers or some other ab activity. Use an abmat, if you want. Feet can be anchored or unanchored, the sit ups can be weighted or unweighted. That’s it. Enjoy!