I have been exercising for a year and have lost three stone. I love my exercise but am now in a rut and want to try something new while focusing on problem areas, eg upper arms, thighs, stomach. What should I do to my regime? In a typical week I currently do one Pilates class, one 40-minute run, a one-mile swim (alternating crawl and backstroke), one combination step, weights and abs class, and one circuit class.

You have a good variety in your present programme - important for injury reduction and overall fitness - but it is very structured and perhaps you are trying to achieve too much in one go. Variety is important, but think seasons. Just as you change your wardrobe with the new seasons, so you can change your workouts. I suggest that each season you focus on a particular objective.

For example, think posture and flexibility in winter (astanga yoga and Pilates with some cardiovascular work), since posture often goes out of the window as we wear thicker clothes and feel the cold more.

In spring, prepare for summer - up the cardio with running and power walking to combat any excess body fat gain from the winter months. In summer, think lean, toned body - get outdoors with interval cardio work and resistance training in the park; take advantage of longer days with increased physical activity.

Concentrate on performance in autumn; try to compete in a charity event. There are some great events abroad - I've taken clients to Paris for a 16km run that starts under the Eiffel Tower and finishes in the gardens at Versailles, to Italy for the Venice marathon, and the south of France for a 20km fun run. And why not build on your new body confidence with classes in something like belly dancing?

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