3 words match “strenuous”

• strenuous adjective

  needing great effort or energy

  The climb to the viewpoint was strenuous but worth it.

  Like arduous, demanding, exhausting

• arduous adjective

  needing a lot of effort and hard work, tiring

  The trek to Everest Base Camp is long and arduous.

  Like difficult, strenuous, grueling

• laborious adjective

  needing a lot of time and hard work

  Planting rice by hand is laborious work.

  Like arduous, strenuous, toilsome