I’ve worked front-line positions and “rear” positions, both. And I know that each come with their stresses. A lot of rear-echelon jobs in the Staff positions are physically comfortable, but come with a lot of mental stress– mostly because of responsibilities.

There is a very old saying, I believe from the Medieval ages:
“Because of a nail, a shoe was lost.
Because of a shoe, a horse was lost.
Because of a horse, a rider was lost.
Because of a rider, a battle was lost.
Because of a battle, a war was lost.
Because of a war, a kingdom fell.”

–the Staff positions are full of people who are responsible for little things like nails and horseshoes. It seems petty. But it is necessary. Still, to the people in immediate physical danger (or in the case of training, immediate physical exertion) the comfortable-looking position of a Staff person seems like an indulgence.

When troops are thinking clearly, they recognize this. But when they are tired, drawn out, sore, sun- and -wind-beaten, and unable to get a comfortable night’s sleep, nerves get raw. So don’t offer to share the air-conditioning necessary to keep the computers running, just quietly do stuff… unless you want to share the ticks!