I tend to gain half a stone or more over the Christmas period. I feel terrible in January, but by the time February comes I've got used to my extra weight and have lost motivation. What can I do to change this?

Adopt a phased approach, which is an effective way to sustain your efforts. Be nice to yourself by making January your posture focus month. Then look to February for a more concerted effort to commence your weight loss, while March is a great month to get outside and boost your cardio fitness.

For the rest of this month, perform 12-16 of these two exercises four times a week. The downward dog leg stretch is great for streamlining your body. Start on all fours, knees under hips and hands under shoulders. Tuck your toes under and push yourself up to an inverted V position so your hips are high. Press your weight back towards your hips, increasing the stretch on the back of your thighs. Keeping the abdominals tight and the hips level, slowly lift one leg, extending it back and contracting your buttocks. Lower and repeat on the other leg.

Side arm openings are great for hunched shoulders. Lie on your side on the floor, legs bent at the hip, knees bent and arms out level from the shoulder. Hold a small weight in your top hand, keep the elbow soft and slowly extend the arm up and over to the other side as in the arc of a circle. Bring the arm back to the start position. Keep the shoulders down and neck long. Complement with side bends, shoulder circles and full body stretches, and ideally a weekly yoga/Pilates or stretch class.

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