吃力 (chī lì): to entail strenuous effort; to toil at a task; strenuous; laborious; strain

He hasn't recovered yet, so even walking a few steps feels very strenuous.

The language of this novel is very difficult, so I read it slowly.

For beginners, this movement might be a bit strenuous.

He climbed to the top of the mountain with great effort, panting heavily.

Carrying heavy objects this way is very strenuous; we need to find a more labor-saving method.