I have been trying to lose a stone and am getting nowhere. I do a variety of exercises, but I get bored. I eat a healthy diet - if I do eat chocolate or a takeaway, I always get back on track. Where am I going wrong ?

I don't think you're doing anything that wrong, but you need to be more strategic. There are two issues here - being savvy about your training and being savvy with your calories.

To lose weight, you have to address what you are eating in calories. Short-term studies have shown this has a greater effect than exercise alone. However, for long-term weight management, exercise is a must. You are eating sensibly and healthily, but you may still be consuming excess calories. You need a kickstart to get moving off the plateau.

For 10 consecutive days, try to eat 1,200-1,500 calories each day (1,400-1,800 for men). Achieve this by operating a double carb curfew - no bread, pasta, rice or potatoes in two of your three meals. It's simple and highly effective. Base these two meals on lean protein, water-packed vegetables and a little essential fat, and ensure the other meal features a slow-releasing carb food group - porridge for breakfast, say, or a blended liquid meal with milk, soaked oats and summer fruits.

With your exercise, address your training as you do your wardrobe - think seasonal. Just as you change your clothes with the months, do the same with your exercise. For example, January is a month to focus on posture, while September is a time to rethink schedules as summer draws to a close and a new school term begins.

While the underlying theme is expending more energy than you are consuming, being seasonal with your fitness can be a refreshing and effective way to keep you moving and keep your weight in check.

· Joanna Hall is a fitness expert (joannahall.com). Send your exercise questions to: Weekend, 119 Farringdon Road, London EC1R 3ER (weekend@theguardian.com).