Swimming regularly is one of the quickest ways to increase all three key areas of fitness: strength, stamina and cardiovascular activity. It uses all the major muscle groups, improves joint flexibility and circulation, and is considered a particularly soothing sport for stressed-out minds. No wonder it's so popular with super-sylphs like Paris Hilton and Courteney Cox.

It's also very low impact – in plain English, this means that because water supports your body weight and reduces the effect of gravity by an amazing 90%, it hugely reduces the risk of muscular injuries that are common in higher-impact activities like running. This means it's a good choice if your activities are restricted by weight problems, or if you're pregnant (but always check with your GP first).

Getting started
Check your local swimming-pool timetable. Most pools have 'sunriser' programmes so you can swim before work, and 'lane-swimming/adult-only' sessions in the evenings. These will ensure you get the most from your session without having to dodge exuberant groups of splashing, screaming children.

Also ask about classes. These run at several levels, from accomplished swimmers wanting to hone their 'form', to complete beginners. You can always improve your swimming style, and taking yourself to the next level will keep swimming fresh and challenging. If you're up to a competitive level, find out about entering the swimming club's forthcoming events or if you're feeling really brave visit the Outdoor Swimming Society.

Strokes
Some of the most popular are crawl, breast stroke and back stroke. All of these will burn between at least 260 and 285 calories per half hour, while toning upper body, torso, buttocks and legs simultaneously. Each type of stroke uses muscles in different patterns, so vary your strokes in each session for maximum results.

For confident and fit swimmers, there's also the butterfly stroke – famously the most difficult and tiring, but amazing for toning the chest, back and upper arms, as well as developing excellent core stability while burning up 330-plus calories per half hour.

Equipment
A comfortable swimsuit is all you need. Goggles are also recommended if you wear contact lenses, or if you think your eyes might be sensitive to pool chemicals or salt water.

You can vary routines using additional equipment to help focus on one area of the body at a time. A foam kickboard will support your upper-body weight while you work on your legs, and a foam pullbuoy is useful for holding your legs still while you concentrate on using your upper-body strokes only.

Holidays
Holidays are the perfect time to swim more frequently, as you're likely have either a pool or a beach nearby. Just remember your sunscreen, and always check what the locals are doing before you swim on an unfamiliar beach - in case there are strong currents or other hidden dangers.

Apart from the joy of not having to blow-dry your hair and get dressed and undressed every time you swim on holiday, there's something wonderfully liberating about splashing around playfully, almost weightless, in the sunshine. So go on, release your inner mermaid!