A friend of mine calls it ‘the rat haunch’. That position we get into when working at a computer, perched on the edge of our seat, hunched over the keyboard, chin poking forward to look at the screen … and then hold it for several hours.
Please have a look at an ergonomics website to find out how to set up your workstation. And, you owe it to your body to give it some regular exercise after all that sitting. So walk, swim, play badminton, football, anything, just avoid more sitting in your free time.
If you spend a lot of time in the car, make seat design a priority when you next choose a car. Thatcham provide useful information on the merits of different makes and models. Your driving position should have your hips and knees bent at 60 degrees, back rest slightly tilted, seat close enough that you can rest your wrists on the top of the steering wheel. Regardless of how comfortable your seat is, however, get out and walk around every couple of hours to give your back a rest.
Osteopaths can help with the effects of poor posture and advise on how to improve it, but only you can make the every day changes that will improve your long-term health.