1) Arduous 2) Backbreaking 3) Effortful 4) Grueling 5) Gruelling 6) Hard 7) Heavy 8) Laborious 9) Like hard labor 10) Punishing 
• (a.) Attended with toil, or fatigue and pain; laborious; wearisome; as, toilsome work.
Toil'some (-sŭm) adjective Attended with toil, or fatigue and pain; laborious; wearisome; as, toilsome work. « What can be toilsome in these pleasant walks?» Milton. -- Toil'some*ly , adverb -- Toil'some*ness ,