No matter how you look at it, half an hour isn’t much time in the whole scheme of things. Heck, you probably waste that much time every day flipping through channels with the remote.

That same thirty ticks of the clock, though, can mean everything to your physical fitness program.

While Olympic athletes and pros may spend hours a day honing their skills and building their bodies, the average man or woman can build a solid fitness base by engaging in 30 minutes of aerobic and weight-bearing activity at least four times a week.

What you do during this time isn’t quite as important as how hard you do it. There are so many choices for the fitness-minded now, it is almost more intimidating to choose a method than it is to actually get going.

Mindful of the plethora of possibilities in the fitness world, here’s a look at some of the simpler aerobic outlets for your pent-up energy:

• Walking -- The simplest and most overlooked of activities, walking can do wonders for your mind and body. We’re not talking about a stroll in the park, though! Depending on your initial fitness level, a half-hour walk can take you almost three miles. At the fastest, most comfortable pace you can manage, you will not only burn calories, but also tone muscles in your legs and hips. Add in some light hand weights and your upper body will get a decent workout, too. As you get fitter, your walking can become quicker and more "powerful" as you increase stride length as well as stride frequency.

  The hidden benefit in walking is mental. Safer and less explosive than some of our other options, walking allows you to take in the scenery as you travel through the highways, byways and around your block. You can mull over a particular problem, or simply enjoy the sights and sounds.

• Running -- After you learn to walk, the next step is learning to run. Running or jogging puts measurably more stress on your joints and connective tissue, but with a proper warmup and a mind attuned to your body you should be able to see steady improvement in your fitness.

  Ease into your run with five to ten minutes at a slower pace. When you feel your body is loose and ready to go, push the pace some and see how it feels to shift gears. You will know you’ve hit your optimal pace when you feel a comfortable rhythm in your breathing and stride.

  If you get bored with a simple run, you can add some speed play -- the Swedish call it fartlek. Put simply, fartlek involves throwing in a fast segment at various times during your run. Kinda like goosing the gas pedal on an open stretch in the country, you might say!

  Safety is a bigger issue for runners than walkers, due in no small part to the concentration it takes to move at a fast pace. Keep an eye on traffic if you run in busy areas, and also watch out for those pesky pets we call dogs. Though they may nudge you into an impromptu fartlek session, canines on the prowl are best avoided if you value your trendy running togs.

• Swimming -- You say you can’t swim very well? No problem. As long as you can keep your head above water, you can get a thorough aerobic workout. Running side to side in the shallow end may not endear you to the maniacal lap swimmers, but it’s a great way to get your heart beating faster. Use a similar motion to your dry-land run, but with a more vigorous arm action. This will work almost every major muscle group, and you won’t even notice you are sweating!

  The more adventurous waterbugs among you can try running in the deep end with the aid of a piece of equipment called an "aqua-jogger". Priced in the $50 region and available from running supply stores, this vest helps you stay vertical in the water. Propel yourself around the pool with a cycling/running motion, and you get the benefits of running without the pounding on your body.