Great Garth!

On Tuesday in Los Angeles, Jennie Garth appeared to be relishing her morning workout -- listening to some tunes and sweating it out, makeup-free, in her workout clothes.

Wearing a baseball cap, blue sweats and a lime-green sports top, the 40-year-old actress showed off her taut, lean physique -- particularly her enviable flat, rock-hard mid-section -- as she exercised near the home she shares with her three daughters Luca, 15, Lola, 9, and Fiona, 5.

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The former Beverly Hills, 90210 actress, 40, has definitely bounced back after her 16-year relationship with husband Peter Facinelli crumbled this past spring --channelling her heartbreak into a body makeover.

"Your body changes with your emotional state of mind," explained the 5-foot-5 star, who is down to a size-26 pants and lost 20 pounds in three months.

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The sunny blonde achieved the new shape through hard work. "She did a lot of outdoor activities: running, hiking, and riding her horse," a pal recently told Us Weekly.

She also hit local gym Cold Iron Barbell thrice weekly. "We don't use machines here. It's all free weights," co-owner Shannon Stewart tells Us. "We like to do circuits: She'd push over a tractor tire, then do push-ups, then jump rope, do deadlifts and run for a bit."

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Adds Stewart: "She loves how her new body looks and she feels healthier, which is most important."

This article originally appeared on Sweaty Jennie Garth Flaunts Rock-Hard Abs, Goes Without Makeup in Workout Clothes