What word best characterizes an experience that is extremely tiring and demanding?

The word "grueling" is used to describe experiences that are extremely tiring and demanding, often requiring great effort and endurance. It conveys a sense of hardship and challenges that can lead to physical or mental exhaustion. For instance, a grueling workout session or a lengthy and intense work shift would leave someone feeling drained and fatigued.

In contrast, options like "relaxing," "easy," and "simple" suggest experiences that are the opposite of tiring or demanding. "Relaxing" implies a calming and restorative nature, while "easy" and "simple" denote tasks or experiences that do not require much effort or cause stress. Therefore, those alternatives would not fit the context of an experience that is taxing or laborious, making "grueling" the most appropriate word choice.