strenuous

adj

1. Having great vigour or energy; forceful.

   “strenuous exercise”

   “strenuous activity”

2. Requiring great exertion; very laborious.

   “It [Troutbeck] has religious isolation also, for it is several miles—and very strenuous miles in winter—from the parish church at Mungrisdale, and the introduction of the harmonium to the waiting room was due to the zeal of a vicar of many years ago who, in the absence of any other room in the village, obtained permission to use the premises for services, including Sunday School. Most of his successors have continued this self-sacrificing duty.”

   “We can achieve this god‐likeness only by unremitting and strenuous effort of the intellect.”

   “Whether you need to recover from a stressful day, a strenuous workout or even an injury or surgery, restorative yoga may be just the thing for you.”