Herculean annoying arduous backbreaking besetting bothersome burdensome castigatory chastening chastising corrective crushing devitalizing disciplinary draining effortful enervating enfeebling exhausting fatiguesome fatiguing forced hard-earned hard-fought heavy hefty inflictive irksome killing labored laborious onerous operose oppressive painful penal penological plaguey punishing punitive punitory retributive sapping strained straining strenuous stressful tiresome tiring toilsome tough troublesome trying uphill vexatious weakening weariful wearing wearisome wearying