Cycling, cross trainer and tredmill are all for cardio workouts - it's gonna do nothing for your belly, although it may help to lose a couple of inches on your waist, as it did for me. You really should talk to a Personal Trainer at your (local) gym. Otherwise, just do the sit-ups (morning and night) and some of the weights. Another tip is to try to hold your belly in, whenever you can remember, as this will make you belly flatter too. Remember, all this takes time, so don't be expecting miracles within a week!