debilitating
effortful
arduous
burdensome
crippling
devitalizing
difficult
draining
enervating
enfeebling
fatiguesome
fatiguing
grinding
grueling
hard
harsh
heavy
killing
laborious
onerous
oppressive
overburdensome
punishing
sapping
straining
strenuous
stressful
tiresome
tiring
toilsome
trying
tyrannous
weakening
weariful
wearing
wearisome
wearying
weighty
costing
defrosting
frosting