I think a good adjustable ergonomic chair is the best seating solution, but if for some reason you’re not able to use one in your current workspace, and your feet aren’t resting flat on the ground, you may want to consider getting a foot rest. I came across a site that sells portable footrests (I know–you’re thinking what footrests aren’t portable…. but I guess there’s the difference between tucking one under your arm and dragging one behind you like a sled). These footrests weight 4 oz, fold flat, and can fit in a briefcase.