“We see lots of adults being diagnosed as attention deficit hyperactivity disorder (ADHD) (多动症) around age 38,” says Timothy Widens, MD, an professor of psychiatry at Harvard Medical School. “That’s right around the time people start doing more-tasks, juggling jobs, families, a home, and other personal duties，” he says.
But not everyone who slacks on work or forgets appointments has ADHD; there are plenty of other reasons you may be losing attentions. Here are five things that could be sucking your attention span dry.
1. Technology overload
Your computer, cell phone, and iPod all compete for your attention—no wonder you're distracted(心烦意乱)! To a certain point, your brain can act as secretary, keeping you organized and helping with time management. But the more tasks you try to do, the harder it is for you to stay focused on any single task, research shows. Learning basic organizational skills, like writing down responsibilities and maintaining a day planner, can help reduce these problems. So take a break from constant television, Internet, and email floods
2. Lack of sleep
If you’re missing out on enough shut-eye—most likely seven to eight hours a night—you’re probably easy-angry, dealing with mind fog, and have difficulty addressing daily tasks. That’s a normal reaction, says Dr. Widens.
3. Poor job satisfaction
Sure, everyone’s unhappy at work from time to time—maybe your customer presentation failed or your boss gave you a poor performance review. And if a disorganized working environment or a boring project make it difficult to focus, that's completely normal. But if you find that you often can't complete projects，you probably need medical attention, or a new job.
4. Too much stress
Stress takes side affects on concentration. Researchers at the University of Madison found that the relaxation technique can add to your ability to focus on your mind. Another study, from researchers at UCLA, suggests that in adults with ADHD, meditation improves attention and eases symptoms of anxiety and depression.
5. Too little exercise
Mounting evidence suggests that regular exercise can keep your mind sharp and increase learning and memory ability. It’s even more important in adults with ADHD. ” My patients who exercise all report that they see improvement in attention,” says Dr. Widens. Working up a sweat can also help you burn off the extra energy that causes you to feel uncomfortable, and it can help you sleep better at night.
Hopefully after you understand these helpful methods, you become more attentive on what you are doing.

Reasons that You Lose
Passage outline	Supporting details
The     of the passage	To tell us we can improve our concentration by following the five things.
Technology overload	Your computer, cell phone, and iPod all compete for your attention—no wonder you're distracted! So        yourself away from constant television, Internet, and email inundation— just for a break.
Lack of sleep	If you’re missing out on enough shut-eye, you are        to be easy-angry, dealing with mind fog, and have difficulty solving daily tasks.
Poor job	Everyone’s unhappy at work from time to time. When       in a disorganized environment or on a boring project, you find it difficult for you to complete projects.
Too much stress	Stress takes side effects on concentration. Relaxing yourself can       your ability to focus on your mind.
Too little exercise	Mounting evidence suggests that regular exercise can keep your mind sharp and increase learning and memory     .
	After       these helpful methods, you are wished to be more attentive on what you are doing.