Your neck will thank you later.
I spend a lot of time at the computer on a regular basis, and I don’t think my neck appreciates it. I like sitting cross-legged in my office chair, but that means I have to lean forward to type on my keyboard. My feet get cold, okay? If you have the capacity to do so, you should endeavor not to be like me. Whether you’re on your computer for only some of the day or all day, you should endeavor to maintain the best possible desk posture.
The ideal posture has you at arm’s length from your keyboard, your chair height leveled with your hips, and your hands at or below elbow level. If you have a higher chair, it’s okay to lean back to rest your neck, provided you don’t shift too much weight to your lower back. Prolonged periods of sitting is already not great for your lower back, so shifting pressure there is only going to make it worse.
If at all possible, you want a sturdy, adjustable ergonomic chair. If all you have is a chair pilfered from the kitchen table, your spine is going to get sore after prolonged sitting. A yoga ball is also a viable option, provided you can find one that’ll big enough while still fitting in front of your desk. Balancing on a yoga ball while working can help keep your muscles engaged and improve your balance.
If you’ve got stronger legs and enough space, you can also try a standing desk with a cushioned pad on the floor. Standing at the desk alleviates many of the posture-related problems of sitting at the desk, though obviously it’ll weigh a bit on your legs and feet after a while. Standing desks are best for folks who don’t spend a lot of time on the computer.