is similar to: arduous, backbreaking, grueling, gruelling, hard, heavy, laborious, operose, punishing, toilsome | dragging | exhausting, tiring, wearing, wearying | heavy, labored, laboured | labor-intensive, labour-intensive | leaden, plodding | Sisyphean | arduous, straining, strenuous.

see also: difficult, hard.

is the opposite of: effortless.

derivation: effortfulness.