Laboring

a.
  1. That labors; performing labor; esp., performing coarse, heavy work, not requiring skill also, set apart for labor; as, laboring days.
  2. Suffering pain or grief.
    3. Laboring oar ,
    the oar which requires most strength and exertion; often used figuratively; as, to have, or pull, the laboring oar in some difficult undertaking.