grueling
GROO-uh-lingadjMeaning extremely tiring and demanding
Memory hook too tired for anything but GRUEL. After hiking up and down three mountains, Jonah is too tired to eat anything but a bowl of mush, called gruel: the hike was grueling.
After a grueling practice in the heat, the team flopped onto the grass.
In context The race was grueling: fifty miles over rocky trails, through rain and wind, with only two short stops for food.
Similar exhausting, punishing, arduous, strenuous
Opposite easy, relaxing