characterized by hardship, struggle, or great effort; arduous

difficult and characterized by physical hardship or strenuous effort

extremely difficult, challenging, or demanding (usually of a task, mission, or responsibility)

difficult and requiring strenuous effort or endurance

to struggle arduously

to make progress only with great difficulty

difficult and dangerous

the quality of being extremely difficult, demanding, or formidable

leading a plain, hardworking life

untold dangers and difficulties

to make progress with great difficulty or be in a strained situation

difficult to understand because of its complexity or depth, typically referring to writing, language, or academic subjects

abstruse and unfathomable (idiom)

(literary) to be in mourning after the death of a parent

life is hard enough as it is; don't burst my bubble (Internet slang)

to shrink or flinch from no difficulty or danger; to face hazards bravely