Mate, all you're doing is masking the problem!

Even if it's just standing for 30 seconds, walking to the cooler or something... try not to sit still for more than 20 minutes.

Really it all comes down to sitting in a good, supported position with correct posture. If you're slouched forward all the time you'll develop tight front muscles and weak, stretched back muscles, it would pay to try and strengthen them, other wise you'll just get caught in a circle.

If you're in any position for an extended time, your muscles will adapt to it. :-/