Once the Summer arrives I try to cycle about 60 miles a week (building up slowly of course). In the Winter I do nowt. Generally I try to stick to vegitarian only lunches and avoid sandwiches, mayonaise and the like. Limit myself to two cups of char a day. Thus my weight fluctuates between 11.5 stone in the Summer and 12.5 in the Winter.
Also, my Class 1 renewal is late September so I am usually by that time slim, fit and healthy. Thank goodness it isn't in early April
I agree with Sunday Driver. If you are starting out, the thing to remember about exercise is that it is not how out of breath you are but how you are using your energy that determines how benificial it is. Cycling is superb for aerobic fat burning and cardio-vascular improving because of its lower intensisty and typically longer durations (1 hour a ride for example) and a good way to get started. Whereas running, although more tiring, actually burns more glycogen than fat due to its higher intensity and generally shorter durations (more anarobic), be careful to limit your duration when starting out. If you spend two weeks running your nuts off, you may end up in worse shape than when you started. If you have a medical soon, then this will show itself as a high resting heart rate. It is very important to build up slowly, adding to the duration each week and varying the intensity so that you don't just knacker yourself out all the time.