I am stressed, which I know is not good for my health. I exercise regularly and have taken up yoga, but I get anxious within the first 15 minutes of the class. Can you recommend some exercise ideas?

I suspect no single exercise will be able to deal with this issue for you. I am sure you are aware that addressing your lifestyle as a whole is necessary, although I appreciate this is not always as straightforward as it sounds. Don't give up your regular, moderate cardiovascular exercise, because this is an effective way to dissipate excess amounts of the stress hormone cortisol. Persist with the yoga, too - perhaps try a different style or teacher.

With respect to a specific exercise, osteopathic research has shown it is possible to induce a state of physical and mental relaxation. To simulate this, do this exercise at home: put two tennis balls in a sock, tying the end to hold the balls in place. Lie on the floor, keep your knees bent or put your feet on a chair. Place the sock under your head at the spot where it touches the floor. You may need to adjust the balls, so they produce a bit of pressure on the back of your head, but are comfortably supporting your weight. Your chin will be slightly tilted. Let your body relax. Rest on the sock for five to 15 minutes. Your breathing should become easier and your muscle tension should gradually decrease. This can be done daily.

If you've been advised by a doctor not to do specific exercises due to a previous head injury or pain, this may not be appropriate for you, so please check with your GP first.

· Joanna Hall is a fitness expert (joannahall.com).

· Send your exercise questions to Weekend, 119 Farringdon Road, London EC1R 3ER (weekend@theguardian.com).