"strenuous challenge" is an appropriate phrase to use in written English.
It is typically used to refer to something that requires a lot of effort and dedication to overcome. For example: "The job search proved to be a strenuous challenge, but I am proud to say I have successfully found a new position."
SENATOR JOSEPH I. LIEBERMAN, of Connecticut, who is facing a strenuous challenge from Ned Lamont.
Having played an aristocrat of the blood in Downton Abbey, he now rises successfully to the more strenuous challenge of embodying Ibsen's faith in aristocracy of the intellect.
Commander Kuebler used the courtroom session to mount a strenuous challenge to the military judge hearing the case, Col. Peter E. Brownback III of the Army.
Now Jen Lancaster takes up an even more strenuous challenge — in "The Tao of Martha," new at No. 14 on the hardcover nonfiction list, she describes her yearlong efforts to live like Martha Stewart.
Onstage and dancing for 50 straight minutes -- a strenuous challenge for even the most seasoned performer -- the piper evolves from a hotheaded adolescent into a mature and disciplined magician.
While Woosnam relishes returning each year to the scene of his only major triumph, the 55-year-old has found the undulating course to be an increasingly strenuous challenge.
I finally didn't feel like a young girl anymore" Her first two roles in the company's spring season at the New York State Theater provide more strenuous challenges.
With each new triumph, the strenuous challenges gave us a newfound confidence and mindset that the seemingly impossible was possible.
Nevertheless, environmental groups vow to mount a strenuous legal challenge, saying the project imperils waterways and an isolated population of grizzly bears.
According to a Heat official, Mourning had been working out with the team for the past six weeks, his practices growing more strenuous and challenging the last 10 days.
For a less strenuous but still challenging day hike, split off from Longs Peak Trail at Mount Lady Washington and follow the trail to Chasm Lake.
