We're all guilty of the turtle posture at times. I include myself in that.
But I'm lucky enough not to be sat at a desk all day every day.
If you have to sit at a desk, you really need to pay a little attention to your posture to ensure you don't fatigue your postural muscles and cause yourself long-term problems which will take more work to unravel.
If you're not sure how best you can use posture, stretching and exercise to keep you in good health then speak to an osteopath.
An osteopath can have a look at your standing and sitting posture, identify areas of weakness, treat any current aches and pains and help you prevent future problems.
Sometimes, becoming aware of your body and learning how you can help yourself, can be the difference between being comfortable, energetic and happy or aching, tired and miserable!