When I look around my office, I usually find the strange phenomenon that some of my colleagues can sit on their chair for many hours without standing up for a rest. They always complain that the work time is too long which causes them to feel exhausted and dizzy. They can't do their own work well, and also don't want to move after being at home. They often says that their life is full of sadness and nagative things. I have once experienced what they felt too. A few years ago, I always felt weak after sitting on a/my chair for a very long time. I suspected that it was old age, or I was unwell , until I stood up and moved around my office one day, then I found that sitting too much had been slowly ruining my health. The risks of sitting too much also made me feel unconfident and sensitive. From then on, I like to have some exercise snacks during my working time, such as, sprinting up and down the stairs for a few reams (what’s a ream?) , or just walking around my office for a minute. All the things that once made me feel bad and uncomfortable never happen again. I have a smile on my face all the time. So, standing up is the single best thing a person can do to improve theor health. How about you?