All this may be old news to those who put "Start Exercising" at the top of their New Year's Resolutions each year, or those who say "I know I should, but…" when friends or health professionals suggest a regular exercise routine. For many, 20 minutes of aerobic exercise three times a week translates into much more time than the 60 minutes it implies.

If time is your tyrant, the good news is that specialists in health and exercise matters are telling us that short bursts of exercise can be effective, too. Tomporowski believes that any activity that stimulates the nerves and muscles of the body for about 15 to 20 minutes is enough to trigger the benefits in the brain. This can include any manner of aerobic "sparks"—dancing, an early morning walk, a midday office stair climb, engaging children in a game of tag.

Though you can't expect to lose much weight or compete in 10K races with these minimum activity levels, regular aerobic exercise will clear the cobwebs and help your brain to function more efficiently. Parking your car at the far end of the garage and walking to work, and taking the stairs instead of the elevator can be the start of something good.

If Exercise Is So Good For Us, Why Don't We Do It?
"No time" is the reason most people offer when asked why they don't exercise. And it's true; most of our lives are busier than ever before. But the fact is, when something is important, when we are committed, when we really want something, we find the time for it. Look beneath the easy and ready excuse and you may find more complex reasons why people won't start or can't seem to stay with a regular exercise routine.

• Impatience: People want to get in great shape Right Now! Never mind that it took twenty years to get in the shape they're in.
• Unrealistic expectations: Looking for the "perfect body" is a guaranteed set up for failure.
• Denial: Many people are in denial that they might have health problems or suffer a debilitating disease.
• Intimidation: The idea of failure or looking foolish or being a beginner intimidates many people into never starting an exercise program.
• Bad experiences or painful memories: Experiences such as humiliation or sexual abuse, or old feelings of inadequacy or embarrassment can cause resistance to the idea of exercise.

• Lack of fun! If exercise has become a never-ending cycle of great ambition, loss of motivation and ultimately not sticking to your routine, it could be that you're not enjoying it.

Physical exercise is essential to good physical and emotional health and a sense of well being.

If any of these reasons lay beneath the surface of your "not enough time" excuse, consider these suggestions:

• Start slowly.
• Get a buddy.
• Find an activity you like. Find several, if you get bored easily.
• Go for progress not perfection.
• Realize that it may hurt before it feels good.
• Remember healthy bodies come in all shapes and sizes.
• Don't give up. If you miss a day, begin again the next day.
• Be patient. All good things take time.
• Congratulate yourself on your hard work and follow-through.
• Ask for help if you need it.

Starting Out and Sticking to It Exercise is meant to be fun. What a concept! If you've gone too far when starting out—going out too hard, expecting too much, essentially punishing yourself—you may come home feeling bad, meaning you'll be less motivated to go out and do it again tomorrow. And so the negative emotions begin to take control. One woman devised a fun points-based game that helped her stay on track. Giving herself a point for every minute she moved her body beneficially, she rewarded herself every time she reached certain point thresholds within a designated time frame. Her workouts consisted of roller skating or ice skating after work, jogging with the dog, dancing in her living room, walking with friends after dinner, jumping on a neighbor's trampoline—in short, she began working out by pursuing what felt like fun. She enjoyed it, and felt more vital mentally and physically than in years. Physical fitness doesn't appear overnight. It's something that gradually builds up over time. And for fitness and its attendant mental benefits to appear at all, consistency is required. When you do things that you find fun, you're more likely to do them consistently.