Grueling and Humdrum

Grueling adjective - Requiring considerable physical or mental effort.

Humdrum and grueling are semantically related. In some cases you can use "Humdrum" instead an adjective "Grueling".

Humdrum adjective - Causing weariness, restlessness, or lack of interest.

Grueling and humdrum are semantically related. Sometimes you can use "Grueling" instead an adjective "Humdrum".