I've had a few jobs over the years since I turned 16, and most of them required me to be on my feet for the majority of my shift, whether it was ringing people up at a cash register or stocking food, but the job that I have now has me sitting at a computer for the most part. While this might be more comfortable initially, sitting constantly can apparently have some damaging side-effects.
Today's infographic from greenerideal.com details the potential harms in spending too much of your day sitting down. Other than the obvious (more time sitting = less time for exercise = gaining weight) sitting for prolonged periods can not only increase your risk for diabetes, but for heart disease as well.
On the positive side, if you are required to sit at your job, or say in a class, it is better to sit at a more reclined angle rather than straight up or hunched over. Also, just remember to try and be as active as you can for the environment that you're in.
For more information on sitting vs. standing please refer to the infographic below. [Via].20.2k