This video is a great visual way of showing how wrong we can go whilst involved in different activities. The difficulty comes when we lose ourselves in what we are doing, we are busy concentrating on what we are typing on the computer, what we are watching on the telly etc…. taking a little time every now and then to just come back to ourselves and think about how we are sitting whilst typing on the computer or watching the telly. This doesnt have to be a long time, for example if you have just opened an email and are waiting for it to appear on your screen take that time to have a think about how you are sitting. When the adverts come on, rather than forwarding through them use that time to think about how you are sitting have you become slouched.
The more you practice this the more you start to change your habits.