effortful
Herculean
abstruse
arduous
assiduous
backbreaking
brutal
burdensome
complex
critical
crushing
delicate
demanding
difficile
difficult
diligent
elaborate
exacting
forced
formidable
grueling
hairy
hard
hard-earned
hard-fought
heavy
hefty
industrious
intricate
jawbreaking
killing
knotted
knotty
labored
laborious
mean
no picnic
not easy
onerous
oppressive
painful
painstaking
punishing
rigorous
rough
rugged
sedulous
set with thorns
severe