Woo, congratulations!
One of the easiest and hardest things I often have people do is challenge themselves to go 1 week or 1 month without any sugar. At first they find it incredibly difficult and have sugar cravings and they figure that as soon as the week is over they can't wait to consumer sugary things. But quite often, by the end of the week, they'll find they've lost a bit of weight, feel better overall, and that sugar isn't quite the draw it was before.
I myself don't cut all of it out, as then it's possible I may form a craving for it. Instead I've just greatly cut down on it such that I eat very little of it (sugars and simple carbs) such that it satisfies my desire to have it without getting to the point of craving it. Perhaps eventually I'll cut all sugar out, but I'm in good shape now, so I currently don't see a need to completely abstain.
I suppose that (as Silent Buddha says) abdominals are hugely important to anybody.
Heh. Yup. Think of your abdominals as the foundation and strength of everything you do. Everything becomes easier to do as your abdominals get into better shape.
For those that have trouble sitting. There's a plethora of things that could be the cause. Not the least of which is potential curvature of the spine (in not natural but not necessarily harmful ways). That can come about through years of bad posture. Something as simple as having a wallet in a back pants pocket can throw your posture off and cause back problems. If you lie on one side a LOT in such a way as to make your spinal column curve to one side or another. Those are just a few examples.
Much of that can be mitigated such that it is no longer a comfort problem or at least not much of one by working to strengthen your abdominals (yup those and not just your central ones but your obliques [side abdominals] as well), stretching muscles that could pull on your back muscles (like the ones in the back of your upper legs), carefully strengthening your back muscles (walking does this naturally), and stretching in general to keep muscles from tightening up so they don't constantly pull and causes stress to themselves as well as on other parts of the body. And, of course, work on getting a proper sitting posture (so much easier with healthy abs).
Of course, it's always possible that the curvature of the spine (or other physical problems) could be so bad that it is no longer possible to sit in a good sitting position. You'd want to see a real doctor (not a chiropractor) to see if that's the case, however.
Regards,
SB