The nice thing about swimming is that it's a relatively low-maintenance, low-cost sport to take up. Unlike other activities like cycling, rock climbing, or even running (which can cost you up to $140 for a decent pair of shoes), swimming will cost you less than $45 to start.
In fact, you don't even need to leave your chair to stock up on a suit, goggles, and (if your hair is long) swim cap. Suits and goggles are available in all shapes, colors and sizes. Eventually you may want to invest in equipment such as a pull buoy and paddles, or Zoomer fins to supplement and add variety to your workouts.
Next, find a local pool with convenient lap swim hours and commit yourself to two to three visits a week. You really need to make time for a minimum of twice a week, otherwise your progress and comfort in the water will be painfully slow.
Absolute beginners should inquire about lessons, either group or individual. Group lessons may be cheaper, but if you are resourceful enough to make some inquiries, you can find private lessons for a steal.
Try asking your local pool if there are lifeguards willing to give 30-minute lessons on their time off, or if there is a high school swim team with members looking for some extra pocket money. Many teens in swimming programs would jump at the chance to earn extra income this way (it beats mowing the lawn), and a ballpark of $20 per half-hour lesson is a bargain compared to private swim instructors at health and country clubs who charge up to $100 an hour.
If you can afford such lessons, they can be very helpful and motivating, but it's always good to shop around for a low-cost alternative and the instructor with the best credentials. The Internet and personals ads in sports publications are also ways of finding lessons.
If you are completely unaccustomed to the water and are terrified of even getting your face wet, you may want to consider aqua-aerobics as a way of getting started in the pool. Hugely popular with seniors and weight-loss candidates who have no athletic background, this is a low-impact, non-intimidating activity that is a good way to overcome any anxiety you may have as a novice to the pool. Many health clubs and local pools will have aqua-aerobics lessons scheduled, so inquire about it if you are interested.
If you have some swimming background (i.e. you can float and perhaps do a few laps), a local masters program can be a terrific athletic and social outlet for you. It is an organized workout usually taught by a qualified coach who can offer training assistance and advice. You will be sharing a lane with several people and doing lots of interval training, so it may be a different pool experience than what you are used to.
Finally, pool swimming entails a certain amount of skill and knowledge in basic clock reading and metric-distance calculation. Here is a quick lesson:
A pool is normally either 25 yards or 25 meters (short course), or 50 meters long (long course).
A lap is up and back, a length is in one direction.
Thus, a "100" means you swim either two laps in a 25-yard/meter pool, or one lap in a 50-meter pool.
1,500 meters equals a mile, which is 15 laps (or 30 lengths) in a 50-meter pool and 30 laps (60 lengths) in a 25-yard/meter pool.
5 x 200 means you swim four laps in a short-course pool five times. 3 x 500 means you swim 10 lengths in a long-course pool three times.
And so on ...
As for clock reading, any good pool will have pace clocks on either end of the facility within easy view. The red second hand is what you pay attention to, and when it is at 12 o'clock, you are at the top and at 6 o'clock you are at the bottom. So leaving on the top means you start your swim on the 60, while leaving at the bottom means you start your swim at the 30.
Let's say you leave on the top and swim one lap short course. You reach the wall and the clock's second hand is on the 20-second mark (4 o'clock). You have thus completed 50 yards or meters in 1 minute, 20 seconds. If you did another lap 'on the bottom,' that would mean you would have 10 seconds to rest before starting lap #2.
Take the plunge and get started; you'll be surprised how quickly you learn and how easy it is to adapt to swimming as a form of fun fitness.