Emma, 29, says, 'Lack of time is a big factor for us – but we really need to change. My husband James, 30, has diabetes and his unhealthy lifestyle means that he already has high cholesterol. Kai, 4, refuses to eat vegetables, and Keira, 3, and Corey, 1, are picky eaters. I'd love us to all get fit and healthy together – can you help?'

All in the mind

It's one thing putting healthy meals in front of your family, it's quite another to get them to eat them. 'If you want to be slim and healthy you need to start thinking and behaving like slim, healthy people,' says behavioural expert Marisa Peer, author of You Can Be Thin (£10·99, Sphere).

Here are a few ways to change your family's mindset from lazy to healthy:

• Don't eat just because food is there and don't make your children finish everything on their plates. Encourage them to eat healthy food first, so they become full, and don't reward them with sweets or pudding for clearing the plate – the same goes for you.
• Set limits – restrict the time that children watch television or sit at a computer without an activity break to two hours per day.
• Steer clear of sugary, fattening after-school snacks and drinks. If kids get into a routine of eating crisps, sweets or chocolate after school you're setting them up to be adults who always need something sweet at 4 o'clock. Try healthier snacks such as fruit, carrot sticks, air-popped popcorn, or oatcakes with peanut butter.
• Choose role models – get your children to link pleasure with healthy eating and exercise by asking them to imagine what their idols do. Boys really respond to 'warrior eating' – opting for what warriors and athletes eat, and girls respond to the idea of food that will help them have gorgeous skin, hair and teeth. Tell them their favourite sports personality or television star always eats his or her vegetables.
• Don't talk about foods being healthy or unhealthy and don't associate some foods with pleasure and others with deprivation. Forget 'yummy doughnuts' or 'healthy broccoli' and don't call fatty foods 'treats'. If someone needs a pick-me-up, choose something non-food related such as a comic for the kids, a new nail varnish for you or a family outing.

Get moving

Children need at least 60 minutes of active exercise a day to optimise their health and happiness. 'If you or your partner are overweight then your child's chances of becoming an overweight adult are 80 per cent greater than a child of normal weight parents,' says fitness expert Joanna Hall (www.joannahall.com). While your genes play a part, most experts agree that your lifestyle can make a huge difference. 'If you are physically active, then your children are six times more likely to exercise too,' says Joanna. Here's how to get fit together.

• Forget competition. If the children aren't all naturally sporty start with non-competitive games that focus on participation and fun rather than winning and skill, so they don't get put off by losing too many times.
• Don't just think sports – anything that gets you all moving counts. Try a scavenger hunt. Make a list of items for everyone to look for on a walk such as a bottle top, a certain leaf from a tree, or a particular landmark.
• Get grandparents involved. 'History walks' with your child and a grandparent can be a great way for two generations to spend quality time together being active.
• Get them logging – give each member of the family a pedometer and log your steps on a family chart. You could even work out how many steps you take to walk a mile and see how long it takes you to reach a certain destination. Put your eldest child in charge of the chart so that they keep mum and dad in check too.
• Get a friend. Approach your local dog centre and volunteer to walk a dog once a week for them – it's a great way to get even the most unreceptive child out of the house and into the fresh air.

Live healthily

A good diet is the key to a happy, healthy family with bags of energy. This means cutting down on fat, salt and sugar, and including a good mix of lean meat, fish, eggs, wholegrain carbohydrates, fruits and vegetables – remember to aim for five portions of fruit and veg a day for everyone. Healthy eating also lifts your mood (great for stressed, grumpy dads) and keeps the bugs at bay. And remember not to serve up supersize portions – children will only get fat if you overload their plates. Angie Jefferson, dietician for the Fibre Foundation, gives us her tips on getting a balanced meal for all the family.

• Healthy eating needn't be boring. Get the children involved to make healthy food less scary. They can make their own fish fingers using chunks of white fish dipped in egg and then polenta and oven-baked, rather than fried, or top their own pizza bases with lots of fresh veggies and reduced-fat cheese.
• Use star charts to reward healthy eating – do one for mum and dad too so that you can all see who is being healthy.
• Set goals – each week focus on a new goal – perhaps a healthy breakfast, upping your fruit and veg portions, or switching to grilling instead of frying.
• Plan – if you plan what you'd like to eat each week and do a big food shop then you have everything you need to hand. Shop online to save time and stop yourself being tempted by fatty, sugary food.
• Time-savers – ready meals can save you time but serve them with salad or fresh or frozen veg.
• Serve fruit for dessert: think jelly with fruit pieces, fruit kebabs and yogurt dip, or fresh banana or strawberry milkshakes – great for calcium intake.