arduous

/ˈɑːdjuːəs/
/ˈɑːɹd͡ʒuəs/

adjective

  1. Needing or using up much energy; testing powers of endurance.

    "The movement towards a peaceful settlement has been a long and arduous political struggle."

  2. Burning; ardent

  3. Difficult or exhausting to traverse.

Synonyms: burdensome, demanding, exhausting, fatiguing, laborious, onerous, strenuous, strugglesome, wearisome