Strenuous

 The word "strenuous" is an adjective that describes something that requires great effort, energy, or exertion. It suggests an activity or task that is physically or mentally demanding.

Here are a few examples of how "strenuous" can be used in sentences:

1. Climbing Mount Everest is a strenuous endeavor that tests the limits of human endurance.

2. After a strenuous workout at the gym, I felt exhausted but accomplished.

3. The hikers embarked on a strenuous journey through the rugged terrain of the mountains.

4. The job interview was mentally strenuous, as I had to answer challenging questions under pressure.

5. The marathon runners trained for months to prepare their bodies for the strenuous race.

In all these examples, "strenuous" is used to describe activities or tasks that require significant effort, physical or mental strength, and may be challenging or demanding.