frequency? 2 sit ups per hour for 10 hours ama? . On a serious note, 20 sit ups per day for how many days/months?

Buda. You need hard, gruelling exercise to reduce the kitambi. And reduce the beer (considerably ...as in stay away from those OlePolos nyam chom + beer marathons), but don't cut it out completely. Beer has its purposes too (one of which is to cure stress and depression), no point being fit but insane.
About the exercise, playing soccer 3 or 4 times a week is a good way to start (running is very boring and needs monk-like focus) ...lastly, do not be in a hurry. It could take 6 months, even more to see a minor reduction. If exercise becomes part of you, it will be minimal effort and your physique will improve over time.
Join the club.

Or you could wait for the male version of slimpossible.

Sawa McReggae. Still waiting to hear some testimonies from wazuans

Get yourself a roller... just do 20 everyday and report back after 21 days. Halafu, punguza sahani.... I get shocked when, on the rare occasion I visit a joint for lunch, to see how mtu mmoja is served food for like three people. Most shocking is that the guy actually demolishes it... ni kama kula mkate mzima peke yako... to see for yourselves, visit any joint that serves 'traditional foods' kama kosewe..