In the interests of your health as well as your waistline, walk for at least 30 minutes per day. If you take public transport, get off the Tube or bus two stops early and walk the rest of the way; don't take lifts and escalators, and walk short journeys. Just put your heels in your bag and slip your trainers on! 30 minutes of walking at a good pace will burn 100-150 calories, which is pretty significant.
Make the most of your weekends: go for walks with your friends and family, or cycle or roller blade. Get out in the open air and enjoy a bit of Mother Nature for a couple of hours. If rain puts paid to outdoor exercise, go swimming. Mix up lengths, aquaerobics and playing with the kids - it's all good fun.
Prolonged moderate-intensity exercise is also really good for burning fat. It relaxes you too, and if you're out enjoying yourself instead of shut indoors you'll be less likely to take comfort in the biscuit tin!