Design is a job with high tides and low tides. There is a certain rhythm to it. Early in a project you might be doing ethnographic research, brainstorming, participating in workshops, putting together a strategy. This will inevitably be less at your desk. As you dig into a project, sketching, refining, iterating, moving into CAD it will get desk intensive. You might make some sketch models here and there. Then there might be some intense sessions over concept down-selection, and back at your desk to work up production documentation. Then working with engineers, working with factory people, reviewing samples… a lot of these things can happen other places than your desk and it is up to you to find the right balance and groove.
Did you think it would not be at a desk?