Break A Sweat Meaning

(idiomatic) To put effort into something.

Example: To start sweating.
2001, Karon Karter, The Complete Idiot's Guide to the Pilates Method, page 119
  Are you feeling stronger and more energetic, and even—dare I say it—breaking a sweat? No, not a pink-faced, dripping sweat; nevertheless, a little dewy under the arms and around your forehead
2008, The Age, January, "Walkovers blaze a trail for women's equal-pay theory"
  Consider, for instance, that Roger Federer, Novak Djokovic, Marat Safin and even the supposedly out-of-sorts Lleyton Hewitt all won the opening set of their first-round matches 6-0 before barely breaking a sweat in the two sets that followed.
  He succeeded effortlessly, without breaking a sweat.