Since the time beginning man has been sitting down on tree trunks and stumps, on wooden planks and boards, on wooden benches, wooden stools and wooden chairs.
You can sit on a wooden kitchen chair for a long time without any trouble, eating, chatting or working with the computer as well. Just try to do these things in a soft easy chair or a sofa. After a short while your ass is loudly and painfully begging for better conditions, your back (vertebra 4 and 5)is aching and the ischias nerve screems, your legs is numb (there has been many lethal strokes on flights caused by narrow soft seats and immobility!)
I have built very cheap, from scrap strips and plywood, wooden seats for my kayaks.
http://www.kayaker.se/nr8-filer.htm
The seat you see there is glass/epoxied all around, but you can saturate the sitting area with linseedoil as well. If you want to sit a little softer just put a loose piece of foam on the seat.

Take care of your backs, listen to your bodies!

Richard Kohlström